Millimeter-wave Frequency Multipliers Research Articles

An E-Band Transformer-Based ×8 Frequency Multiplier With Enhanced Harmonic Rejection

We present an efficient method of enhancing the harmonic rejection ratio (HRR) of a millimeter-wave frequency multiplier (FM) by utilizing optimal capacitive loads with minimal area overheads. To verify the proposed method, we demonstrate an eight-times FM ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times 8$ </tex-math></inline-formula> FM) with an HRR of 35–50 dBc over a wideband of 20.8 GHz from 70.4 to 91.2 GHz in the 65-nm CMOS technology. The designed <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times 8$ </tex-math></inline-formula> FM comprises three stages of push–push doublers (PPDs), and each PPD is followed by a driving amplifier (DA) to suppress undesirable spurs and provide optimal power levels. The transformer (TF)-based baluns in each PPD are rebalanced using two separate capacitive loads connected to the output terminals of the TF. The proposed technique achieves more than 10 dB of improvement in the HRR for the entire FM chain with a significant bandwidth enhancement in simulation. The fabricated <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times 8$ </tex-math></inline-formula> FM achieves a peak output power of 6.3 dBm at 78.16 GHz with a dc current of 164 mA from a 1.2-V supply voltage. The chip area is 0.95 mm2, including the pads, whereas the core layout area is only 0.35 mm2.

E-Band Frequency Sextupler With &gt;35 dB Harmonics Rejection Over 20 GHz Bandwidth in 55 nm BiCMOS

A frequency multiplier by six (sextupler) for local oscillation (LO) generation in <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$E$ </tex-math></inline-formula> -band is presented. It comprises a tripler, a doubler, and an output buffer. A detailed analysis is proposed to discuss the optimal order of the multiplication stages to minimize the unwanted harmonics of the input. Moreover, novel circuit topologies for the tripler and doubler are introduced. The tripler core is devised to reproduce the transcharacteristic of a third-order polynomial that ideally generates only the third harmonic of a sinusoidal input signal. By leveraging an envelope detector for adaptive biasing, the circuit maintains excellent suppression of the driving signal and unwanted harmonics over wide variations of the input power. The proposed topology improves output signal purity and current conversion efficiency against classical triplers based on the transistors biased in class C. The cascaded frequency doubler is based on a novel push–push configuration that provides a differential output and excellent odd-order harmonic rejection due to an enhanced robustness to amplitude and phase unbalances of the driving signal. The sextupler is fabricated in a 55-nm SiGe-BiCMOS technology. Driven with a 0-dBm input signal and consuming 63.1 mW of dc power, it delivers <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$P_{\mathrm {out}}$ </tex-math></inline-formula> up to 5.6 dBm at 72 GHz. <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$P_{\mathrm {out}}$ </tex-math></inline-formula> is above 0 dBm over 20-GHz bandwidth (BW), while undesired harmonics of the input are suppressed by more than 35 dB. Compared to previously reported millimeter-wave frequency multipliers, the sextupler demonstrates improved harmonic rejection, conversion gain, and efficiency, without compromising the operation BW and output power.

Large Amplitude Torsions in Nitrotoluene Isomers Studied by Rotational Spectroscopy and Quantum Chemistry Calculations.

Rotational spectra of ortho-nitrotoluene (2-NT) and para-nitrotoluene (4-NT) have been recorded at low and room temperatures using a supersonic jet Fourier Transform microwave (MW) spectrometer and a millimeter-wave frequency multiplier chain, respectively. Supported by quantum chemistry calculations, the spectral analysis of pure rotation lines in the vibrational ground state has allowed to characterise the rotational energy, the hyperfine structure due to the 14 N nucleus and the internal rotation splittings arising from the methyl group. For 2-NT, an anisotropic internal rotation of coupled -CH3 and -NO2 torsional motions was identified by quantum chemistry calculations and discussed from the results of the MW analysis. The study of the internal rotation splittings in the spectra of three NT isomers allowed to characterise the internal rotation potentials of the methyl group and to compare them with other mono-substituted toluene derivatives in order to study the isomeric influence on the internal rotation barrier.

Novel Baseband Equivalent Model for Digital Predistortion of Wideband Frequency-Multiplier-Based Millimeter Wave Sources

This article proposes a novel digital predistortion (DPD) scheme for mitigating the effects of nonlinear distortion caused by frequency multipliers when driven with wideband vector modulated signals. An effective pruning strategy is applied to limit the number of coefficients that consequently reduces the complexity of the DPD scheme while maintaining excellent linearization capacity. Extensive tests are conducted using different millimeter-wave frequency multipliers for proof-of-concept validation. These multipliers include two frequency doublers (25 and 28 GHz), a tripler (63 GHz), and a quadrupler (25 GHz), each driven by vector-modulated signals with an instantaneous bandwidth of up to 400 MHz. Using 44 coefficients or less, the proposed DPD approach allows for excellent frequency-doubler distortion cancellation and improves the error vector magnitude (EVM) and adjacent channel power ratio (ACPR) from about 21% and 21 dB to 1.8%-0.8% and 47-54 dB for the different test signals. Similarly, in the case of the frequency tripler, the EVM and ACPR improve from 8% and 30 dB to less than 1.7% and 45-51 dB after applying the proposed DPD scheme with 57 coefficients under different test signals. Finally, in the case of the frequency quadrupler (composed of two cascaded frequency doublers), the proposed DPD scheme achieves the EVM and ACPR of 0.9%-1.6% and 53-45 dB, respectively, with a higher number of coefficients.

A comprehensive study of cryogenic cooled millimeter-wave frequency multipliers based on GaAs Schottky-barrier varactors

AbstractThe benefit of cryogenic cooling on the performance of millimeter-wave GaAs Schottky-barrier varactor-based frequency multipliers has been studied. For this purpose, a dedicated compact model of a GaAs Schottky-barrier varactor using a triple-anode diode stack has been developed for use with a commercial RF and microwave CAD tool. The model implements critical physical phenomena such as thermionic-field emission current transport at cryogenic temperatures, temperature dependent mobility, reverse breakdown, self-heating, and high-field velocity saturation effects. A parallel conduction model is employed in order to include the effect of barrier inhomogeneities which is known to cause deviation from the expected I--V characteristics at cryogenic temperatures. The developed model is shown to accurately fit the I--V --T dataset from 25 to 295 K measured on the varactor diode stack. Harmonic balance simulations using the model are used to predict the efficiency of a millimeter-wave balanced doubler from room to cryogenic temperatures. The estimation is verified experimentally using a 188 GHz balanced doubler cooled down to 77 K. The model has been further verified down to 14 K using a 78 GHz balanced doubler.

A Reconfigurable Multiphase &lt;inline-formula&gt; &lt;tex-math notation="TeX"&gt;$LC$&lt;/tex-math&gt;&lt;/inline-formula&gt;-Ring Structure for Programmable Frequency Multiplication

This brief presents a reconfigurable LC-ring structure and a programmable millimeter-wave low-power frequency multiplier that were combined together to achieve a maximum power-saving effect of 73% depending on operation modes. The proposed multiphase LC ring is reconfigurable to change the number of stages and thereby minimize current consumption depending on the number of phases necessary in an application. The programmable multiplier is implemented to reduce its current consumption by 82% through an inverter-type input circuit. A millimeter-wave frequency multiplier prototype, including the reconfigurable multiphase LC ring, was fully integrated in a 65-nm CMOS process and experimentally verified to provide programmable frequency multiplication over triple frequency bands of 12.6-15.2, 25.2-30.4, and 50.4-60.8 GHz, utilizing a 6.3 to 7.6-GHz multiphase LC ring.

Analysis and optimization of millimeter-wave frequency multipliers by a hybrid genetic algorithm/harmonic balance technique

Analysis and optimization of millimeter-wave frequency multipliers by a hybrid genetic algorithm/harmonic balance technique

A theoretical three-port coaxial-line rectangular-waveguide model and its application to millimeter-wave structures

A theoretical three-port model for a coaxial-line rectangular-waveguide junction is described and evaluated using several different realistic millimeter-wave mount structures. The model is found to be usable with good accuracy over a large variation in mount dimensions. The model is specifically applied in calculations of the embedding impedance seen by the diode in a millimeter-wave frequency multiplier. The three-port model is an improvement over simpler models hitherto used for devices such as millimeter-wave frequency multipliers because it takes into account all parameters in the mount.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>