Subharmonic Mixer Research Articles

A subharmonic front-end in SiGe:C technology for 94-GHz imaging arrays

The design of a subharmonic downconverter for 94-GHz imaging arrays in SiGe:C technology is presented. A three-stage differential low-noise amplifier (LNA) with lumped matching networks is used together with a subharmonic mixer driven by a single-pole local-oscillator poly-phase network to form the front-end. The LNA yields 15 dB gain at 94 GHz, while the mixer provides 5 dB conversion gain over a 10 GHz IF bandwidth. The integrated downconverter provides 20 dB conversion gain at 94 GHz with an input 1-dB compression point of −31 dBm and has a current consumption of 45 mA at a 3.3 V supply voltage. The total required die area of the complete downconverter (excluding pad frame) is 0.1 mm, thus making it particularly suitable as a front-end in multi-channel receiver systems.

Q-Band pHEMT and mHEMT Subharmonic Gilbert Upconversion Mixers

This letter makes a comparison between Q-band 0.15 mum pseudomorphic high electron mobility transistor (pHEMT) and metamorphic high electron mobility transistor (mHEMT) stacked-LO subharmonic upconversion mixers in terms of gain, isolation and linearity. In general, a 0.15 mum mHEMT device has a higher transconductance and cutoff frequency than a 0.15 mum pHEMT does. Thus, the conversion gain of the mHEMT is higher than that of the pHEMT in the active Gilbert mixer design. The Q-band stacked-LO subharmonic upconversion mixers using the pHEMT and mHEMT technologies have conversion gain of -7.1 dB and -0.2 dB, respectively. The pHEMT upconversion mixer has an OIP3 of -12 dBm and an OP1 dB of -24 dBm, while the mHEMT one shows a 4 dB improvement on linearity for the difference between the OIP3 and OP1 dB. Both the chip sizes are the same at 1.3 mm times 0.9 mm.

$Ka/Ku$-Band pHEMT Gilbert Mixers With Polyphase and Coupled-Line Quadrature Generators

In this paper, three kinds of Kalpha/Ku-band Gilbert mixers are demonstrated using 0.15- mum AlGaAs/InGaAs pseudomorphic high electron mobility transistor technology. Thanks to the semiinsulating GaAs substrate, microwave passive components have a low-loss feature, and polyphase filters work up to higher frequencies. Highly accurate tantalum-nitride thin-film resistors utilized in polyphase filters result in perfect quadrature operation. Therefore, our proposed single-sideband up-converter operates at 15 GHz with a 63-dB sideband rejection ratio, and another 34-GHz in-phase/quadrature (I/Q) subharmonic down-converter reaches <0.4-dB magnitude and < 1deg phase errors. More than 50-dB local oscillator (LO) leakage suppression is achieved in the I/Q subharmonic mixer. On the other hand, a 40-GHz stacked-LO subharmonic mixer with a novel compensation technique is also proposed and demonstrated to improve LO speed and reduce the amount of transistors, as compared to previous work.

A Frequency Tripler Using a Subharmonic Mixer and Fundamental Cancellation

A new odd-order frequency multiplier topology is demonstrated in this work that uses a subharmonic mixer to realize a frequency tripler. A feedforward circuit is used for fundamental cancellation at the output and eliminates the need for filtering structures. For demonstrative purposes, and to validate the concept, a 1-3-GHz proof-of-concept frequency tripler circuit was fabricated. The tripler circuit achieved a measured output fundamental suppression of up to 30 dB below the third harmonic and a conversion gain of up to 3 dB. The circuit was implemented in CMOS 0.18-mum technology and the chip area was 0.8 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> including bonding pads.

A 5-GHz-Band CMOS Receiver With Low LO Self-Mixing Front End

A 5.0-GHz-band monolithic direct-conversion receiver front end employing subharmonic mixers (SHMs) is demonstrated in 0.18-mum CMOS technology. Instead of using transistors as transconductors, the SHMs adopt on-chip 1:4 transformers to achieve voltage gain, and hence, excellent local-oscillator self-mixing suppression and good linearity can be obtained. Additionally, a CMOS-compatible postprocess is used to selectively remove the silicon substrate underneath the inductors and transformers of the receiver front end. While dissipating 43.9 mW from a 1.8-V supply, the micromachined receiver front end exhibits a voltage gain of 28.0 dB, a noise figure of 9.7 dB, a third-order input intercept point of -7.8 dBm at 5.0 GHz, and an input-referred dc offset of -118.0 dBm. The proposed receiver front end is further integrated with analog baseband circuits, a fractional-N frequency synthesizer, and a serial-to-parallel data converter to accomplish a multioperation-mode receiver.

Design of Submillimeter Schottky Mixers Under Flat-Band Conditions Using an Improved Drift-Diffusion Model

Minimum conversion loss in millimeter and submillimeter-wave Schottky mixers is achieved when the diodes are slightly pushed into the flat-band regime. The discrepancies found between experimental results and physics-based harmonic balance simulations for a 330 GHz antiparallel diode pair subharmonic Schottky mixer showed that traditional drift-diffusion models with conventional boundary conditions at the Schottky contact do not correctly predict the behavior of the Schottky-based mixers working under flat-band conditions. In this work, we employ Monte Carlo simulations to get physical insight of the Schottky diodes working in the flat band regime. New boundary conditions obtained from this analysis have been included in our drift-diffusion simulator which has resulted in an improvement of our circuit simulator to predict mixer operation under flat band regime.

A 320–360 GHz Subharmonically Pumped Image Rejection Mixer Using Planar Schottky Diodes

This letter presents the design, fabrication and test of an integrated 320-360 GHz subharmonic image rejection mixer using planar Schottky diodes. The integrated circuit uses two separate anti-parallel pairs of diodes mounted onto a single quartz-based circuit. Measurement results give best single sideband (SSB) receiver noise temperatures of approximately 3400 K at 340 GHz, with an image rejection from 7.2 to 24.1 dB over the 320-360 GHz frequency band. This work represents the first demonstration of a Schottky based SSB mixer at submillimeter wavelengths.

A 10–40 GHz Broadband Subharmonic Monolithic Mixer in 0.18 $\mu$m CMOS Technology

A 10-40 GHz broadband subharmonic monolithic passive mixer using the standard 0.18 mum CMOS process is demonstrated. The proposed mixer is composed of a two-stage Wilkinson power combiner, a short stub and a low-pass filter. Likewise, the mixer utilizes a pair of anti-parallel gate-drain-connected diodes to achieve subharmonic mixing mechanism. The two-stage Wilkinson power combiner is used to excite a radio frequency (RF) and local oscillation (LO) signals into diodes and to perform broadband operation. The low-pass filter supports an IF frequency range from dc to 2.5 GHz. This proposed configuration leads to a die size of less than 1.1 times 0.67 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The measured results demonstrate a conversion loss of 15.6-17.6 dB, an LO-to-RF isolation better than 12 dB, a high 2LO-to-RF isolation of 51-59 dB over 10-40 GHz RF bandwidth, and a 1 dB compression power of 8 dBm.

A 16-31 GHz MINIATURE QUADRUPLE SUBHARMONIC MONOLITHIC MIXER WITH LUMPED DIPLEXER

A novel 16{31GHz quadruple subharmonic monolithic passive mixer with a chip dimension of 0:82 £ 0:7mm 2 is designed and fabricated using the 0.15m GaAs pHEMT process. The novel conflguration of the quadruple subharmonic mixer consists of a lumped frequency diplexer and a low-pass fllter utilizing a pair of anti-parallel Schottky barrier diode to achieve quadruple subharmonic mixing mechanism. The lumped frequency diplexer formed with a low-pass network and a high-pass network is used to reduce the chip dimension while operating at low frequency band and to improve the isolation between the RF and LO ports with a broadband operation. The low- pass fllter supports an IF frequency range from DC to 2.5GHz. From the measured results, the mixer exhibits a 12.5{16.5dB conversion loss, a LO-to-RF isolation better than 15dB, a 50{59dB high 4LO- to-RF isolation over 16{31GHz RF bandwidth, and an input 1dB compression power of 2dBm.

INTEGRATED COMPACT BROAD KA-BAND SUB-HARMONIC SINGLE SIDEBAND UP-CONVERTER MMIC

Design, simulation and measurement results of the integrated compact up-converter MMICs (microwave monolithic integrated circuits) are presented and discussed. The design is performed to achieve low cost and high performance transmitter system for the Ka-band frequency applications. It is designed using anti- parallel diode pair sub-harmonic single sideband mixer and three stage RF (radio frequency) amplifler. Microstrip lines and lumped elements are used together to achieve a compact chip size. The layouts of the circuits are designed with careful EM (electromagnetic) simulations to avoid inter-component couplings and efiect of the microstrip bending discontinuities. The chip is operated for the wide bandwidth of the RF frequency from 22{38GHz. Due to sub-harmonic mixing the required local oscillator frequency (LO) is reduced to half (10{19GHz) to that of the RF frequency. The conversion gain of the chip is 9{ 15dB and Pi1dB output power is 7{12dBm. The single sideband and anti-parallel diode pair suppress the in-band unwanted sideband and second harmonic of the local oscillator (2LO), respectively. The suppression of sideband and 2LO signals is typically 20{35dB and 20{ 30dB, respectively. The size of the chip is as compact as 4.2mm 2 on a 100m-thick GaAs substrate.

Ultra-high-order self-oscillating mixers based on multiple-element technique

Novel design approaches for ultra-high-order subharmonic self-oscillating mixers (SOMs) based on a multiple-element technique are presented. They are of high impact for high-end millimetre-wave systems as subharmonic operation reduces local oscillator frequency requirements. An outline of the basic theory and a design procedure for arbitrary high mixing orders are presented, and a sixth-order SOM is fabricated for the first time. The prototype exhibits a conversion gain of +2.8 dB at an RF input frequency of 7.4 GHz.

Wide-Band Single-Side Band Subharmonic Mixer Constructed With Re-Entrant Couplers and Lumped-Element Coupler

This work presents a new configuration of single-side band (SSB) harmonically pumped mixer implemented by using two kinds of wide-band quadrature couplers to achieve the characteristics of wide operation bandwidth, high side band suppression and compact circuit size. A new type of 3 dB re-entrant microstrip coupler, which is easy to integrate with the surface-mounted devices, is adopted to achieve the required quadrature phase shifts of the radio frequency (RF) and local oscillation signals. The lump-element type of intermediate frequency coupler is not only able to have broadband characteristics and compact circuit size, but also provide the low-pass filtering function to eliminate the low-pass filter of the mixer in the conventional design. An experimental prototype of the proposed SSB mixer was manufactured. The measured conversion losses of the prototype, which includes the losses caused by couplers, are lower than 13 dB. It also shows greater than 20 dB side-band suppression over the RF frequency range of 2.2 to 2.85 GHz and the measured side-band suppression at some RF frequencies are up to 45 dB. The size of the S-band prototype fabricated on FR4 PCB is only about 40 x 45 mm2.

A 170 GHz 45$^{\circ}$ Hybrid for Submillimeter Wave Sideband Separating Subharmonic Mixers

We present a 135deg/45deg phase shifter hybrid intended to be used in subharmonic sideband separation mixer schemes at submillimeter-wave frequencies. The design consists of an increased height 90deg 6-arm branch guide coupler with a three stub loaded differential line 45deg phase shifter at the output. The device has been implemented at G-band in an E-plane WR-05 splitblock design with a center frequency of 170 GHz and 15 % bandwidth. Measured S-parameter are in good agreement with simulations showing an isolation and return loss better than 20 dB and an amplitude and phase imbalance within 0.4 dB and 2deg, respectively.

A 60 GHz retrodirective array system with efficient power management for wireless multimedia sensor server applications

A 60 GHz retrodirective array system with efficient power management for wireless multimedia sensor server applications is proposed. The system consists of three sections: a retrodirective array, a local oscillator (LO) and a power management system. The proposed system is able to efficiently control battery power by turning off when it is not in use. In particular, the power management circuit controls the power of the LO by a rectenna for efficient battery operation. Although there is no interrogating signal, the system is in a sleeping mode where extremely low power consumption occurs. When the system is interrogated by an RF signal, the system is awaken and starts consuming full power. When the received power density is larger than 0.013 mW/cm2, the system turns on and starts working as a retrodirective array. Furthermore, the proposed system can avoid the use of an expensive LO by employing a fourth subharmonic mixer. Experimental data are used to verify the proposed idea.

A Compact 60 GHz Integrated Up-Converter Using Miniature Transformer Couplers With 5 dB Conversion Gain

A 60 GHz singly balanced subharmonic up-converter is presented in this letter. The monolithic microwave integrated circuit (MMIC) chip is implemented using a standard 0.13 mu m mixed-signal/radio frequency (RF) CMOS process. This circuit combines a subharmonic mixer and a three-stage cascode output amplifier. A new miniature transformer coupler is used to provide the local oscillation (LO) signals with 90 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">deg</sup> phase difference to achieve subharmonic mixing. This MMIC demonstrates a conversion gain of 5 dB for RF frequency from 58 to 66 GHz, and the 2LO-to-RF isolation is over 40 dB. The chip size is only 0.366 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .

A 30–100 GHz Wideband Sub-Harmonic Active Mixer in 90 nm CMOS Technology

This letter presents a 30-100 GHz wideband and compact fully integrated sub-harmonic Gilbert-cell mixer using 90 nm standard CMOS technology. The sub-harmonic pumped scheme with advantages of high port isolation and low local oscillation frequency operation is selected in millimeter-wave mixer design. A distributed transconductance stage and a high impedance compensation line are introduced to achieve the flatness of conversion gain over broad bandwidth. The CMOS sub-harmonic Gilbert-cell mixer exhibits -1.5 plusmn 1.5 dB measured conversion gain from 30 to 100 GHz with a compact chip size of 0.35 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The OP <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dB</sub> of the mixer is -10.4 dBm and -9.6 dBm at 77 and 94 GHz, respectively. To the best of our knowledge, the monolithic microwave integrated circuit is the first CMOS Gilbert-cell mixer operating up to 100 GHz.

A 5-GHz Subharmonic Injection-Locked Oscillator and Self-Oscillating Mixer

This paper presents a multifunctional circuit realizing the functions of oscillation, mixing, amplification, and frequency multiplication at 5 GHz. A theoretical and experimental description of the circuit is given. The proposed circuit, which combines both the injection-locking and mixing processes, uses only one port where both the RF/intermediate frequency signal and the injection signal (IS) are applied. The IS, which is used to stabilize the oscillation, is at a subharmonic of the oscillation frequency (omegaosc/4) having a power level as low as -50 dBm. Calculations of the phase noise and measurements of the mixing properties are reported which indicate a noise improvement, and a high up-conversion gain. The implementation of the circuit exhibits an up-conversion gain of 14 dB, a phase noise of -110 dBc/Hz at 100-kHz offset, a dB of -15 dBm, a third-order intercept point of -2 dBm, and a power consumption of 35 mW. Calculated and measured results are in good agreement for all cases, emphasizing the relevance of the proposed circuit.

Low-Power Short-Range Radio CMOS Subharmonic RF Front-End Using CG-CS LNA

A 2.4-GHz fully integrated differential RF front-end was designed and implemented using 0.18-mum CMOS process. This design was targeted for low-power and low-cost applications such as short-range radio in biomedical devices. This RF front-end consists of a common-gate common-source low-noise-amplifier, a frequency doubler passive subharmonic mixer, and a resistive source degeneration intermediate frequency buffer. It consumes 2.5 mA from a 1.8-V supply. It occupies 950 mum times500 mum active area, which is only approximately 30% of that of the conventional RF front-end. This subharmonic RF front-end achieves 26-dB conversion gain, 9-dB noise figure and -10-dBm IIP3.

A Novel Circuit Architecture for High Performance of High-order Subharmonic Mixers

A novel circuit architecture for high performance of high-order subharmonic (SH) mixers is proposed in this paper. According to the specified harmonic mixing order, one or more mixer diodes sub-arrays and corresponding power divider as well as phase shift network for RF and LO signals are arranged in the circuit. This proposed SH mixer circuit has improved conversion loss, wide dynamic range and high port isolation for high-order SH mixers. By phase cancellation of idle frequencies, the proposed SH mixer circuit can eliminate complicated design procedure of idle frequency circuits; by phase cancellation of leakage LO power to RF and IF port, and leakage RF power to LO port, the mixer circuit can get high port isolation in LO-IF/RF and RF-LO. The increased antiparallel diode pairs in each sub-array will also lead to well performance by lowering effective series resistance. The proposed SH mixer circuit can be easily realized with power divider and phase shift network for RF and LO signals.

A Ka Band Balanced Third LO-Harmonic Mixer Using a Lumped-Elements Quadrature Hybrid

A novel configuration of a subharmonic mixer utilizing third local oscillation (LO) harmonic is presented. The mixer is capable of down-converting a Ka-Band radio frequency (RF) signal with the third harmonic of an X-band LO signal to produce a 2 GHz intermediate frequency signal. It is fabricated on a 4 mil substrate using a 0.15 mum GaAs PHEMT process. A novel quadrature hybrid is realized by using compact lumped elements, and it is beneficial for the reduction of chip size for an LO at a relatively low frequency in this topology. This is because it does not need any bulky via holes. Compared with published subharmonic mixers, it provides a more flexible requirement for an LO source at a relatively low frequency for an overall communication system design. The measured results show that the best conversion loss is about 13.2 dB at a RF frequency of 29 GHz as a 10.5 dBm 9 GHz LO signal is pumped. The chip area of the mixer is less than 3.14 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .