Output Matching Research Articles

Robustness of GaN on SiC low‐noise amplifiers in common source and cascode configurations for X‐band applications

SummaryCascode HEMTs exhibit high gain and broadband performance. Promising reverse transmission makes matching networks simpler and insensitive to impedance on either side of the HEMT. On the other hand, common source (CS) HEMTs with intentional small inductance at the source provide simultaneous match for optimum noise and input impedance. This paper provides a performance comparison of μm cascode HEMTs‐based low‐noise amplifier and μm CS HEMTs‐based low‐noise amplifiers with specific emphasis on robustness, including survivability and reverse recovery time (RRT). Cascode LNA survives an input power of 33 dBm while CS LNA handles 30 dBm power, each having a 1 k passive limiting resistor on the gate bias line. RRT of cascode LNA is also better. Better survivability and RRT for cascode LNA are attributed to its HEMT's stacked configuration. The designs of LNAs are described, along with their small‐signal, noise, and large‐signal characteristics in the X‐band. Cascode LNA has a better input match, while CS LNA has a better output match. Gains are comparable, while CS LNA has better P1dB at higher band edge frequency. The noise figure for both LNAs is less than 1.9 dB, with CS LNA having a slight edge over cascode. This study benefits RF designers in choosing appropriate HEMT topology as per application for designing robust low‐noise amplifiers.

Model matching problems for impulsive linear systems with polytopic uncertainties

This work deals with the problem of designing a feedback compensator that forces the output of a linear system with abrupt discontinuities in the state evolution and polytopic uncertainties to match that of a given model with the same features. First, the case in which the system and the model are initialized at zero and output matching is required to be exact is considered. Then, the case in which, for arbitrary initialization, output matching is required to be asymptotic for sufficiently slow sequences of the time instants wherein the state exhibits abrupt discontinuities is studied. In addition, on the assumption that the model is stable for sufficiently slow jump time sequences, also the further requirement that asymptotic output matching be achieved with stability of the compensated system is investigated. Constructive, directly checkable, solvability conditions for the problems addressed are derived by leveraging on appropriate structural notions and geometric tools. Algorithmic procedures for the synthesis of the compensators, when the solvability conditions are met, are devised. Some illustrative examples conclude the work.

Inverted sequential load-modulated balanced amplifier for extending dynamic power range over wide bandwidth

This paper propose an inverted sequential load-modulated balanced amplifier (ISLMBA) for extending the dynamic power range of a power amplifier (PA) over a wide bandwidth. The proposed ISLMBA consists of a control amplifier (CA) and a balanced PA (BPA) pair. A composited impedance inverter is inserted between each BPA transistor and the output coupler. The composited impedance inverter is composed by the intrinsic elements and output matching network (OMN) of the BPA transistor. In this way, the intrinsic elements can be fully absorbed into the impedance inverter over a wide bandwidth. Meanwhile, the load modulation trajectories of the BPA transistors can be optimized over a wide bandwidth by tuning the characteristic impedance of the impedance inverter. The theoretical current, voltage and load-modulation profiles of the ISLMBA are comprehensively analyzed. It is illustrated that the proposed ISLMBA could maintain high efficiency at deep output back-off power level over a wide bandwidth. Moreover, this work designs and fabricates an ISLMBA operating over 1.3–2.55 GHz to verify the proposed PA architecture. The fabricated ISLMBA exhibits a saturation drain efficiency (DE) of 54.5%–73.8% and a saturation output power of 42.9–45.9 dBm. At the same time, the fabricated ISLMBA achieves a 10 dB back-off DE of 42.1%–63.9% over the frequency band of interest. When the fabricated ISLMBA is stimulated by a 20 MHz wideband signal with a peak-to-average power ratio (PAPR) of 10.2 dB at 2.0 GHz, the measured adjacent channel leakage ratios (after predistortion) are −47.7 and −48.8 dBc at the lower and upper bands, respectively.

Joint MCS Adaptation and RB Allocation in Cellular Networks Based on Deep Reinforcement Learning With Stable Matching

Joint modulation-coding scheme (MCS) adaptation and resource block (RB) allocation is an effective approach to guarantee different quality of service (QoS) requirements of all UEs under dynamic network environments. In this paper, we consider a fifth generation (5 G) cellular network with time-varying wireless channels, in which the BS serves multiple user equipments (UEs) under limited available RBs. We aim to minimize the total RB consumption subject to the rigorous constraints of each UE's QoS requirement. To attain this objective, this paper puts forth an online learning technique, referred to as integrated Deep Reinforcement learning and stable Matching (DeepRM), in the sense that the MCS adaptation and RB allocation decisions are conducted without acquiring the real-time channel quality indicator (CQI) feedback. DeepRM is a closed-loop framework, where the output of deep reinforcement learning (DRL) is imported into the stable matching to guide optimal RB allocation whilst the output of stable matching is fed into the DRL framework to assist efficient MCS decision-making. Specifically, in DeepRM, we first develop a powerful DRL algorithm, termed as Action-and-Reward Branching Deep Q-network (ARBDQ), by incorporating the action branch architecture into conventional DRL and modifying the traditional deep neural network training mechanism, to perform judicious MCS decisions on different links in parallel. Then, a new many-to-one stable matching algorithm, called adaptive deferred acceptance, is exploited to dynamically adjust the RB quota of each UE in a computationally efficient fashion. Simulation results demonstrate that compared with ACO-HM, OLLA-ADA, and ARBDQ-Random algorithms, DeepRM induces much less RB consumption while guaranteeing the QoS requirements of all UEs in various network scenarios. Furthermore, under miscellaneous QoS requirement, number of UEs, and CQI reporting period setups, DeepRM is more robust than other baselines.

Recovering Generalization via Pre-Training-Like Knowledge Distillation for Out-of-Distribution Visual Question Answering

With the emergence of large-scale multi-modal foundation models, significant improvements have been made towards Visual Question Answering (VQA) in recent years via the “Pre-training and Fine-tuning” paradigm. However, the fine-tuned VQA model, which is more specialized for the downstream training data, may fail to generalize well when there is a distribution shift between the training and test data, which is defined as the Out-of-Distribution (OOD) problem. An intuitive way to solve this problem is to transfer the common knowledge from the foundation model to the fine-tuned VQA model via knowledge distillation for better generalization. However, the generality of distilled knowledge based on the task-specific training data is questionable due to the bias between the training and test data. An ideal way is to adopt the pre-training data to distill the common knowledge shared by the training and OOD test samples, which however is impracticable due to the huge size of pre-training data. Based on the above considerations, in this paper, we propose a method, named Pre-training-like Knowledge Distillation (PKD), to imitate the pre-training feature distribution and leverage it to distill the common knowledge, which can improve the generalization performance of the fine-tuned model for OOD VQA. Specifically, we first leverage the in-domain VQA data as guidance and adopt two cross-modal feature prediction networks, which are learned under the supervision of image-text matching loss and feature divergence loss, to estimate pre-training-like vision and text features. Next, we conduct feature-level distillation by explicitly integrating the downstream VQA input features with the predicted pre-training-like features through a memory mechanism. In the meantime, we also conduct model-level distillation by constraining the image-text matching output of the downstream VQA model and the output of the foundation model for the pre-training-like image and text features. Extensive experiments on the VQA-CP v2 and VQA v2 datasets demonstrate the effectiveness of our method.

A circuit solving method for output matching network parameters of Doherty power amplifiers

In this paper, all possible numerical solutions are provided when the matching conditions for Doherty power amplifier (DPA) back-off and saturation states are met. Firstly, this article presents an impedance expression of the DPA. Then all circuit parameter solutions can be solved for the load modulation of DPA using this expression. In the process of solving circuit parameters, the impedance matching of the DPA at the saturation level is established through the analysis of the S-parameter matrix. Then by limiting the impedance solution range of DPA at the output power back-off (OBO) level, the circuit parameter solutions that satisfy the specified conditions are meticulously screened. The output matching network of the DPA is designed according to the obtained circuit parameter solutions for broadband operation. To validate the proposed design method, a broadband DPA operating from 1.2 to 2.4 GHz is designed and measured based on the proposed method. Under the continuous wave excitation, the measured drain efficiency at 6 dB OBO level and saturation (SAT) level are 44%–56% and 51%-65.4% from 1.2 to 2.2 GHz, respectively. The peak output power is 45.1–46.3 dBm.

A Combined N/PFET CFET-Based Design and Logic Technology Framework for CMOS Applications

We propose a new technology and design platform using combined common gate N/PFET CFET as basic element for CMOS circuit applications. Two CFET unit structures, namely common gate (CG) and N-gate (NG), are identified to form base design elements. Through the two units, all circuit logic functions in standard cell library and SRAM can be realized without significant process complication. A Multi-gradient Neural Network (MNN) based SPICE compact modeling methodology is developed for these CFET units. As an example, MNN model generation is illustrated for CG with the output matching well with the TCAD data within and beyond the range of model extraction. Circuit simulations are exercised using the MNN models and demonstrated successfully the expected circuit functionalities. As the CFET technology be adopted as mainstream in future, this novel design framework proposed would enable efficient logic design.

Asymmetrical Sequential Load Modulated Balanced Amplifier With Composited Impedance Inverter and Reciprocal Mode for Broadband Applications

In this paper, the design of a broadband asymmetrical sequential load modulation balanced amplifier (ASLMBA) is presented. The composited impedance inverters, which contain the intrinsic elements and the output matching networks (OMNs) of the balanced power amplifier (BPA) transistors, are inserted before the output coupler of the BPA pair. In this way, optimal matching condition of the BPA transistors can be maintained over a wide bandwidth. In addition, to ensure an optimal load modulation trajectory of the control amplifier (CA) without over-saturation, a reciprocal mode is applied to the BPA pair by elaborately changing the turn-on sequence of the sub-amplifiers, which is affected by the composited impedance inverter and the OMN of the control amplifier. It is illustrated that the proposed ASLMBA can effectively maintain high efficiency over an extended dynamic range and a wide bandwidth. As a proof of concept, a broadband ASLMBA working over 1.35-2.55 GHz is designed and measured in this work. Experimental results show that the designed ASLMBA achieves a saturation output power of 43.2-45.1 dBm with a saturation gain of 6.5-10.5 dB and a saturation drain efficiency (DE) of 57.8-77.7%. Meanwhile, the 6 dB and 10 dB back-off DEs of the designed ASLMBA are 51.3-66.6% and 47.7-68.9%, respectively.

A low-cost 24 GHz single-stage amplifier using SICL based stepped impedance matching network

This paper presents a single-stage amplifier using substrate-integrated coaxial line (SICL) technology. It is implemented with a low-cost PCB technique at 23.35–24.05 GHz. The size of the proposed amplifier is 4.9λg×1.1λg where λg is the guided wavelength at the center frequency. In this circuit, a SICL-based bias-tee network is designed where the mounting pads are introduced for the integration of the components, such as transistor and capacitor. Next, with the help of de-embedding techniques, the input and output matching networks are designed in the SICL environment at 24 GHz. The proposed amplifier circuit exhibits 9.2 dB of peak gain with less than 1 dB of gain ripple and more than 10 dB of input/output return losses in the operating frequency band of 23.35–24.05 GHz. Moreover, the elementary blocks of the amplifier are presented in the circuit. Based on the appropriate modeling of the amplifier’s elementary blocks, the simulated and measured results are in good agreement.

Continuous Class-J/F-1 Mode Asymmetrical Doherty Power Amplifier With Extended Bandwidth and Enhanced Efficiency

This article presents a design method of continuous class-J/F <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-1}$</tex-math> </inline-formula> mode asymmetrical Doherty power amplifier (DPA) using the phase tuning technique. By properly adjusting the phase characteristics of the output matching network (OMN) of the carrier amplifier (CA) and the harmonic impedances of the postmatching network (PMN), the load impedance of CA can be effectively tuned to meet the impedance requirements of continuous class-J and continuous class-F <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-1}$</tex-math> </inline-formula> modes at the power back-off point, which thus extends the bandwidth with enhanced power back-off efficiency. In addition, the proposed DPA can theoretically achieve saturation efficiency of more than 58.7% over the working frequency. Based on the proposed method, a broadband continuous class-J/F <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-1}$</tex-math> </inline-formula> mode asymmetrical DPA operating from 1.3 to 2.5 GHz (63%) is designed and measured. Under the continuous wave stimulation, the measured 9-dB back-off, 6-dB back-off, and saturation efficiencies are 55%–62.5%, 52.4%–65.6%, and 62.5%–81%, respectively. The measured 9-dB back-off and saturation gains are 8.8–11.3 and 7–10.6 dB, respectively. When driven by a 20-MHz long-term evolution (LTE) modulated signal with 9.9-dB peak-to-average power ratio (PAPR), the measured average efficiency is 47%–59% and the adjacent channel power ratio is from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-$</tex-math> </inline-formula> 23.6 to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-$</tex-math> </inline-formula> 31.7 dBc.

Dual-Band Power Amplifier With Bandwidth Extension Based on Broadband Harmonic Control Part Dual Transmission Line

This paper presents a dual-band (DB) high-efficiency power amplifier (PA) with extended bandwidth. A novel output matching network (OMN) that integrates harmonic control into DB fundamental matching design is proposed. Bandwidth of the DB PA can be efficiently extended by the OMN presented since it can offer DB broadband harmonic control while maintaining the input impedance at DB fundamentals. By precise control of the characteristic impedance on the part dual transmission line (part-DTL) and the double shunt stub (DSS), these two structures are made equivalent to the series and parallel transmission line (TL) performance at DB fundamentals. Additionally, the part-DTL modulates the input impedance in broadband near DB harmonics to pure reactive, and the DSS optimizes the imaginary part of the input impedance at DB harmonics. For validation, a DB PA is designed and fabricated with a Cree CGH40010F GaN transistor. The fabricated DB PA features the saturated output power of 42.4 dBm and 41.7 dBm with the power-added efficiency of 73.5% and 68.4% at 2.6 GHz and 3.5 GHz, respectively. Specially, the bandwidth of the DB PA is extended to over 300 MHz and 200 MHz.

Research on the identification method of key parts of ship target based on contour matching

A template matching method based on the contour fitting heading angle is proposed for the problem of identifying key parts of maritime ships. First, unmanned boats are used as hypothetical enemy targets to extract outer contours, build a matching template library, and establish relevant kinematic models. Based on the requirements of timeliness and relativism, the judgment conditions for fitting angles and heading angles are given. A traversal fitting framework is established based on the structural similarity index algorithm, and the target matching template is matched based on precise matching results. A motion space that combines position correlation, electro-optical detection distance, and target pitch decoupling is designed to obtain real heading angles. Finally, based on the relative position information of the template’s key parts, the key parts of the target are matched, and the normalized output matching image is obtained. The experiment shows that this method can achieve recognition instructions in real seaways where key parts of the target cannot be extracted due to the large amount of water mist, and it has advantages in timeliness, accuracy, and applicability compared with other algorithms. This method has strong robustness and provides a reference for the identification of key parts of various types of ship targets.

A 24-30GHz Power Amplifier with &gt;20-dBm Psat and &lt;0.1-dB AM-AM Distortion for 5G Applications in 130-nm SiGe BiCMOS

This paper presents a power amplifier (PA) designed as a part of a transceiver front-end fabricated in 130-nm SiGe BiCMOS. The PA shares its output antenna port with a low noise amplifier using a low-loss transmission/reception switch. The output matching network of the PA is designed to provide high output power, low AM-AM distortion, and uniform performance over frequencies in the range of 24.25-29.5 GHz. Measurements of the front-end in TX mode demonstrate peak S21 of 30.3 dB at 26.7 GHz, S21 3-dB bandwidth of 9.8 GHz from 22.2 to 32.0 GHz, and saturated output power (Psat) above 20 dBm with power-added efficiency (PAE) above 22% from 24 to 30 GHz. For a 64-QAM 400 MHz bandwidth orthogonal frequency division multiplexing (OFDM) signal, -25 dBc error vector magnitude (EVM) is measured at an average output power of 12.3 dBm and average PAE of 8.8%. The PA achieves a competitive ITRS FoM of 92.9.

A High-Efficiency Inverse Class-F GaN MMIC Power Amplifier With Compact Output Matching Network

This brief presents a high-efficiency inverse Class-F (Class-F-1) monolithic microwave integrated circuit (MMIC) power amplifier (PA) fabricated with 0.25-lm GaN-on-Si technology. The design is based on a compact output matching network (COMN), which consists of a harmonic control circuit (HCC), an L-section matching circuit and a bias line. In order to reduce the circuit area that make it suitable for monolithic integration, the HCC uses only three transmission lines to achieve the second and third harmonic control. In addition, the conventional quarter-wave bias line is replaced with a shorter, proper one. The proposed COMN simplifies the matching network while realizing Class-F-1 operation, which improves efficiency, output power and reduce chip size. The maximum power added efficiency of 64.5% is achieved at 3.0 GHz, with an output power of 38.4 dBm and a power gain of 10.3 dB.

Optimization and demonstration of a bidirectional output linear-cavity fiber laser with a record high power of 2 × 4 kW

The bidirectional output fiber laser can achieve two laser outputs from a single resonant cavity, which can reduce the volume and cost of high-power fiber laser systems and has good application prospects in the industry. In this work, we demonstrated a bidirectional output fiber laser oscillator structure, and a total output power of 8 kW at the 2 ports × 4 kW level was achieved experimentally for the first time. In order to suppress stimulated Raman scattering (SRS) and transverse mode instability (TMI), the double cladding ytterbium-doped fiber with a core/cladding diameter of 30/400 µm, a pair of matched output coupler fiber Bragg gratings (OCFBG) with a 3 dB bandwidth of 2 nm, and the pump source with wavelength-stabilized 981 nm laser diodes (LDs) were employed. The effect of the coiling method and diameter of the active fiber on the optical-to-optical (O-O) efficiency and TMI threshold were studied intensively. The comparison of laser performance with a unidirectional output oscillator was further exploited, and results indicated that the bidirectional output fiber laser oscillator possessed a higher O-O efficiency and TMI threshold. By optimizing the fiber coiling diameter and coiling method, we finally achieved a total laser output power of 8169 W (3769 W at end A and 4400 W at end B), with an efficiency of 74.6% and beam quality of M2A ∼ 2.13, M2B ∼ 2.36, while the total output power achieved by unidirectional output structure was only 5805 W with signs of TMI. To the best of our knowledge, it is the highest output power of the bidirectional output fiber laser.

Automation of Customer Support System (Chatbot) to Solve Web Based Financial and Payment Application Service

One of the most important features of any online service is the quality of its customer care. However, with the development of NLP tools, businesses are considering automated chatbot solutions to keep up with the increasing demand for their products and services. In view of this, the chatbot was developed using AIML java interpreter library Program AB which helps match input and output predefined in the AIML file. AIML (Artificial Intelligence Markup Language) was used to preprocess and train the bot using ready-made AIML file for FAQ questions. Also, vaadin was used to build a web UI to interact with the trained AIML bot. Finally, a google script was written to translate from any language to English for the bot to understand and send the response in the preferred language of the user. Findings showed that the response time of the bot is dependent of the network, as the design gave a score of 70%, 80%, 90% and 90% for load testing, stability, reliability testing and usability testing, respectively. Also, the bot is compatible with different operating systems, both for forward compatibility and backward compatibility having a score of 95%. The bot was able to answer customer questions, enquiries and complaints and the response time of the bot depends on the strength of the network since it is web based. Hence, the system provided a simple, cheaper, and durable customer financial and payment application service. Since chatbots cannot answer all questions, businesses that decide to implement them should ensure that they have enough protections in place against attacks and that routine requests are standardised to ensure optimal performance.

A Wideband Power Amplifier in 65 nm CMOS Covering 25.8 GHz–36.9 GHz by Staggering Tuned MCRs

Broadband millimeter-wave power amplifiers have attracted much attention and have wide applications for 5G communication, satellite communication, radar, sensing, etc. Yet, it is challenging to design a power amplifier with broadband small-signal gain and power performance simultaneously. In this study, a transformer-based symmetrical magnetically coupled resonator (MCR) matching network for broadband output matching and stagger-tuned MCRs are used to achieve both broadband small- and large-signal performance. Also, to enhance the gain for the power amplifier, a three-stage common-source pseudo-differential structure is adopted to mitigate the low-gain issue due to stagger tuning, and the shunt resistors aimed to decrease the Q factor of the MCRs. We used the in-phase two-way current combined with microstrip transmission lines to increase the output power. Designed in 65 nm bulky CMOS technology, the power amplifier presents a 3 dB small-signal gain bandwidth from 25.8 GHz to 36.9 GHz, indicating a peak gain of 25.87 dB at 30.5 GHz. The power amplifier demonstrates a 17.84 dBm saturated output power (Psat) at 31 GHz and a 24.37% peak power added efficiency (PAEmax) at 28 GHz. The power amplifier achieves a flat Psat of 17.44 ± 0.4 dBm, a PAEmax of 22.59 ± 1.78%, and an OP1dB of 13.78 ± 0.31 dBm from 26 GHz to 36 GHz.

An improved harmonics suppression power amplifier circuit using integrated self‐resonant capacitor for radar application

SummaryIn order to ensure that the electromagnetic compatibility and mutual interference of multiple radar network systems meet the requirements, a 55‐W gallium nitride (GaN) high harmonics suppression (HSs) high power amplifier (HPA) microwave monolithic integrated circuit (MMIC) with an operating frequency of 5.1–6.3 GHz is designed for radar network system. An HSs method using self‐resonant capacitor integrated in the output matching network of HPA is proposed to improve the HSs characteristics. The measured results show that under the condition of 100‐μs pulse width and 10% duty cycle, the HSs are greater than 48 dBc while the output power is greater than 55 W, the power gain is 21 dB, and the power additional efficiency (PAE) is 54%, which is suitable for use in radar network system. The size of the HPA is 3.55 × 4.05 mm2.

High-Efficiency and Cost-Effective 10 W Broadband Continuous Class-J Mode Quasi-MMIC Power Amplifier Design Utilizing 0.25 μm GaN/SiC and GaAs IPD Technology for 5G NR n77 and n78 Bands

This paper presents two power amplifiers designed for 5G NR n77 and n78 bands. These power amplifiers were fabricated using WINTM Semiconductors’ 0.25 μm GaN/SiC technology and GaAs IPD technology. To achieve a reduction in costs, GaAs IPD technology was incorporated in the design, leading to the realization of a quasi-monolithic microwave integrated circuit design. To ensure high power, high efficiency, and broadband operation, a continuous Class-J mode output matching network was utilized. The power amplifier with split chip-on-board wire-bond assembly had a power gain of 21.7 dB, a 3 dB power bandwidth ranging from 2.85 GHz to 4.48 GHz, a saturation power of 40.3 dBm, and a peak power-added efficiency of 39.5%. On the other hand, the power amplifier with stack chip-on-board wire-bond assembly had a power gain of 21.7 dB, a 3 dB power bandwidth ranging from 2.84 GHz to 4.47 GHz, a saturation power of 40 dBm, and a peak power-added efficiency of 36.5%. For a 5G NR FR1 256-QAM 100-MHz bandwidth modulated signal with a frequency range of 3.3 GHz to 4.2 GHz, both the split and stack chip-on-board wire-bond assembly power amplifiers achieved average output powers of 29.6 dBm and 28.3 dBm, respectively. These output powers were measured under an error vector magnitude requirement of 3.5%.

False positives are common in single-station template matching

Template matching has become a cornerstone technique of observational seismology. By taking known events, and scanning them against a continuous record, new events smaller than the signal-to-noise ratio can be found, substantially improving the magnitude of completeness of earthquake catalogues. Template matching is normally used in an array setting, however as we move into the era of planetary seismology, we are likely to apply template matching for very small arrays or even single stations. Given the high impact of planetary seismology studies on our understanding of the structure and dynamics of non-Earth bodies, it is important to assess the reliability of template matching in the small-n setting. Towards this goal, we estimate a lower bound on the rate of false positives for single-station template matching by examining the behaviour of correlations of totally uncorrelated white noise. We find that, for typical processing regimes and match thresholds, false positives are likely quite common. We must therefore be exceptionally careful when considering the output of template matching in the small-n setting.