It is known that designing an LNA for its minimum noise figure (NF) is not the best if the design... more It is known that designing an LNA for its minimum noise figure (NF) is not the best if the design goal is the lowest NF of the entire receiver (RX). A better LNA performance metric is the noise measure (NM). However, if feedback is allowed, the minimum NM can be realized with different combinations of NF and available gain, depending on which the RX NF changes. This paper theoretically studies the low-noise performance limit of an RX when lossless feedback is applied to its LNA. Somewhat counterintuitively, the lowest possible RX NF is shown to be realized when the LNA NM is slightly off its minimum NM. A new noise performance metric, $\Xi$, is introduced. The RX NF is shown to be minimized when $\Xi$ of LNA is minimized. Unlike NM, $\Xi$ is applicable even when the first stage of an RX is passive, as in a passive-mixer-first THz RX.
Coulomb blockade devices can circumvent some of the problems that arise from the continuing minia... more Coulomb blockade devices can circumvent some of the problems that arise from the continuing miniaturization of conventional circuits. However, device miniaturization and higher circuit integration aggravate cross-coupling phenomena in Coulomb blockade circuits. As an example, a silicon-based bidirectional electron pump was electrically characterized with emphasis on cross-coupling arising from the clock signal driving the pump. The cross-coupling alters profoundly the expected device characteristics, and the experimental data are confirmed by Monte Carlo simulations.
This paper presents an experimentally found device-size-independent universal relationship betwee... more This paper presents an experimentally found device-size-independent universal relationship between the settling time of floating-body silicon-on-insulator (SOI) metal–oxide–semiconductor field-effect transistors (MOSFETs) and the substrate current in body-tied devices. Such a relationship could enable one to characterize dynamic properties of SOI MOSFETs through DC measurements and would be useful for physical compact modeling of history effects.
This paper reports a CMOS power amplifier (PA) designed considering the performance degradation o... more This paper reports a CMOS power amplifier (PA) designed considering the performance degradation of MOSFETs caused by both temperature variations and the hot-carrier effect. A small-signal MOSFET model that reproduces the transient degradation caused by the hot-carrier effect is proposed. A 79 GHz CMOS PA was designed utilizing the proposed small-signal model. Simulation results agreed well with the measurement results of the PA fabricated with a 40 nm CMOS technology. It achieved the small-signal gain variations of below 0.7 dB and the OP1dB degradation of less than 0.8 dB in the temperature range of 0°C to 100°C.
The gain and the stability of composite amplifiers consisting of a core 2-port amplifier and a lo... more The gain and the stability of composite amplifiers consisting of a core 2-port amplifier and a lossless reciprocal embedding network is studied theoretically with particular interest in the design of near-fmax amplifiers. Design equations for finding an optimal embedding network that gives the highest MAG (maximum available gain) under a given stability requirement are presented. How such an embedding network could be synthesized is briefly sketched.
In this paper, a 1-meter high-speed-wireless data transmission, employing a 300-GHz CMOS RF front... more In this paper, a 1-meter high-speed-wireless data transmission, employing a 300-GHz CMOS RF front end and Cassegrain antennas, is demonstrated. To improve system SNR of the CMOS RF front end, high-gain antennas are designed for the 300-GHz frequency bands. The antenna shows the peak antenna gain of 40 dBi and the 3-dB beamwidth of 1.3 degrees, within the diameter of 6 cm. In the wireless demonstration, the maximum data rate of 36 Gb/s with QPSK modulation is achieved due to high gain antennas.
A 28.5-GHz fifth-order Chebyshev bandpass filter (BPF) with a 2-GHz bandwidth (7% fractional band... more A 28.5-GHz fifth-order Chebyshev bandpass filter (BPF) with a 2-GHz bandwidth (7% fractional bandwidth) built of silica-based post-wall waveguide (PWW) is presented for 5G applications. The dielectric loss tangent of the substrate is as low as 0.00036 at 44 GHz. The coupled resonators are designed in such a way that the sizes of the resonators are nearly the same, while still allowing the coupling between them to be well-controlled. The dimensions of the BPF is 11×10 mm2. The insertion loss of the BPF, not including the I/O interfaces for probing measurement, is less than 0.8 dB. Two designs of I/O interfaces for the PWW-based BPF are also presented.
It is known that designing an LNA for its minimum noise figure (NF) is not the best if the design... more It is known that designing an LNA for its minimum noise figure (NF) is not the best if the design goal is the lowest NF of the entire receiver (RX). A better LNA performance metric is the noise measure (NM). However, if feedback is allowed, the minimum NM can be realized with different combinations of NF and available gain, depending on which the RX NF changes. This paper theoretically studies the low-noise performance limit of an RX when lossless feedback is applied to its LNA. Somewhat counterintuitively, the lowest possible RX NF is shown to be realized when the LNA NM is slightly off its minimum NM. A new noise performance metric, $\Xi$, is introduced. The RX NF is shown to be minimized when $\Xi$ of LNA is minimized. Unlike NM, $\Xi$ is applicable even when the first stage of an RX is passive, as in a passive-mixer-first THz RX.
Coulomb blockade devices can circumvent some of the problems that arise from the continuing minia... more Coulomb blockade devices can circumvent some of the problems that arise from the continuing miniaturization of conventional circuits. However, device miniaturization and higher circuit integration aggravate cross-coupling phenomena in Coulomb blockade circuits. As an example, a silicon-based bidirectional electron pump was electrically characterized with emphasis on cross-coupling arising from the clock signal driving the pump. The cross-coupling alters profoundly the expected device characteristics, and the experimental data are confirmed by Monte Carlo simulations.
This paper presents an experimentally found device-size-independent universal relationship betwee... more This paper presents an experimentally found device-size-independent universal relationship between the settling time of floating-body silicon-on-insulator (SOI) metal–oxide–semiconductor field-effect transistors (MOSFETs) and the substrate current in body-tied devices. Such a relationship could enable one to characterize dynamic properties of SOI MOSFETs through DC measurements and would be useful for physical compact modeling of history effects.
This paper reports a CMOS power amplifier (PA) designed considering the performance degradation o... more This paper reports a CMOS power amplifier (PA) designed considering the performance degradation of MOSFETs caused by both temperature variations and the hot-carrier effect. A small-signal MOSFET model that reproduces the transient degradation caused by the hot-carrier effect is proposed. A 79 GHz CMOS PA was designed utilizing the proposed small-signal model. Simulation results agreed well with the measurement results of the PA fabricated with a 40 nm CMOS technology. It achieved the small-signal gain variations of below 0.7 dB and the OP1dB degradation of less than 0.8 dB in the temperature range of 0°C to 100°C.
The gain and the stability of composite amplifiers consisting of a core 2-port amplifier and a lo... more The gain and the stability of composite amplifiers consisting of a core 2-port amplifier and a lossless reciprocal embedding network is studied theoretically with particular interest in the design of near-fmax amplifiers. Design equations for finding an optimal embedding network that gives the highest MAG (maximum available gain) under a given stability requirement are presented. How such an embedding network could be synthesized is briefly sketched.
In this paper, a 1-meter high-speed-wireless data transmission, employing a 300-GHz CMOS RF front... more In this paper, a 1-meter high-speed-wireless data transmission, employing a 300-GHz CMOS RF front end and Cassegrain antennas, is demonstrated. To improve system SNR of the CMOS RF front end, high-gain antennas are designed for the 300-GHz frequency bands. The antenna shows the peak antenna gain of 40 dBi and the 3-dB beamwidth of 1.3 degrees, within the diameter of 6 cm. In the wireless demonstration, the maximum data rate of 36 Gb/s with QPSK modulation is achieved due to high gain antennas.
A 28.5-GHz fifth-order Chebyshev bandpass filter (BPF) with a 2-GHz bandwidth (7% fractional band... more A 28.5-GHz fifth-order Chebyshev bandpass filter (BPF) with a 2-GHz bandwidth (7% fractional bandwidth) built of silica-based post-wall waveguide (PWW) is presented for 5G applications. The dielectric loss tangent of the substrate is as low as 0.00036 at 44 GHz. The coupled resonators are designed in such a way that the sizes of the resonators are nearly the same, while still allowing the coupling between them to be well-controlled. The dimensions of the BPF is 11×10 mm2. The insertion loss of the BPF, not including the I/O interfaces for probing measurement, is less than 0.8 dB. Two designs of I/O interfaces for the PWW-based BPF are also presented.
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Papers by Shuhei Amakawa