Isolating Bandpass Filters Using Time-Modulated Resonators

In this paper, we demonstrate, for the first time, an isolating bandpass filter with low-loss forward transmission and high reverse isolation by modulating its constituent resonators. To understand the operating principle behind the device, we develop a spectral domain analysis method and show that the same-frequency nonreciprocity is a result of the nonreciprocal frequency conversion to the intermodulation (IM) frequencies by the time-varying resonators. With appropriate modulation frequency, modulation depth, and phase delay, the signal power at the IM frequencies is converted back to the RF frequency and adds up constructively to form a low-loss forward passband, whereas they add up destructively in the reverse direction to create the isolation. To validate the theory, a lumped-element three-pole 0.04-dB ripple isolating filter with a center frequency of 200 MHz and a ripple bandwidth of 30 MHz is designed, simulated, and measured. When modulated with a sinusoidal frequency of 30 MHz, a modulation index of 0.25, and an incremental phase difference of 45°, the filter achieves a forward insertion loss of 1.5 dB and a reverse isolation of 20 dB. The measured nonmodulated and modulated results agree very well with the simulations. Such nonreciprocal filters may find applications in wideband simultaneous transmit and receive radio front ends.

Isolating Bandpass Filters Using Time-Modulated Resonators

In this paper, we demonstrate, for the first time, an isolating bandpass filter with low-loss forward transmission and high reverse isolation by modulating its constituent resonators. To understand the operating principle behind the device, we develop a spectral domain analysis method and show that the same-frequency nonreciprocity is a result of the nonreciprocal frequency conversion to the intermodulation (IM) frequencies by the time-varying resonators. With appropriate modulation frequency, modulation depth, and phase delay, the signal power at the IM frequencies is converted back to the RF frequency and adds up constructively to form a low-loss forward passband, whereas they add up destructively in the reverse direction to create the isolation. To validate the theory, a lumped-element three-pole 0.04-dB ripple isolating filter with a center frequency of 200 MHz and a ripple bandwidth of 30 MHz is designed, simulated, and measured. When modulated with a sinusoidal frequency of 30 MHz, a modulation index of 0.25, and an incremental phase difference of 45°, the filter achieves a forward insertion loss of 1.5 dB and a reverse isolation of 20 dB. The measured nonmodulated and modulated results agree very well with the simulations. Such nonreciprocal filters may find applications in wideband simultaneous transmit and receive radio front ends.

Differential CMOS Low Noise Amplifier Design for Wireless Receivers

This article presents the differential CMOS-LNA design for wireless receiver at the frequency of 3.4GHz. This differential 𝑳𝑵𝑨 provides less noise figure (NF), high gain and good reverse isolation as well as good stability. The designed LNA is simulated with a 180 nanometers CMOS process in cadence virtuoso tool and simulate the results by using SpectreRF simulator. This LNA exhibits a NF of 0.7dB, a high voltage gain of 28dB, and good reverse isolation (S12) of -70dB. It produces an input and output reflection coefficient (S11) of - 6.5dB and (S22) of -14dB, and it maintains good stability of Rollet factor Kf > 1, and also alternate stability factor B1f < 1, respectively.

Optimization of building blocks for multi-stage 17–44 dB 6.1–9.6 mW 90-nm K-band front-ends

In this article, five two-stage ∼6-mW and four three-stage ∼9-mW matched amplifier architectures are proposed to establish optimization procedure and quantify relative merits of cascode (CC), common-gate (CG), and commonsource (CS) building blocks for low-voltage low-power multi-stage front-ends. The circuits are simulated with a 90-nm CMOS technology including modeling of layout parasites. Integrated bias trees and passive port matching networks are incorporated in the K-band designs. In the face of process mismatch, variability in noise and gain figures remains <0.39 dB and <7.1 dB from the design values. The five combinations of building blocks in twostage low-power (6.1–6.6 mW) amplifiers achieve linearity (IIP3) in the range of −5.2∼–13.5 dBm, good reverse isolation (better than −26 dB), 2.89–3.82 dB noise penalties, and 17.2–25.5 dB peak forward gain. In case of threestage front-ends built with CS, CC, and CG blocks (power rating 9.2–9.6 mW), forward gain and optimized noise figures are found as >33 dB and <3.26 dB, respectively. They achieve −2.5∼18.3 dBm IIP3, <−39 dB reverse isolation, and <−17 dB minimum IRL. The results are compared with reported simulated findings on CMOS multistage amplifiers to highlight their relative advantages in terms of power requirement and decibel(gain)-per-watt.