Session 22 — High frequency analog techniques

Summary form only given. This session presents analog techniques applied to high-frequency applications found in RF systems & data acquisition systems. The first paper presents a tunable low-pass filter from 34-314 MHz with a 22 dBm IIP3 while consuming only 4.6 mW. The 3
^rd
-order filter is constructed from inverter-based g
_m
-cells and non-linear MOSCAPs, leveraging several distortion cancellation techniques. Additionally the filter resistors and capacitors are used to self-compensate the negative feedback circuits resulting in lower power and a very small circuit area of 0.007 mm
²
. The second paper presents a tunable RF bandpass filter with Q-tuning implemented in a 0.13 μm SiGe BiCMOS process. The filter is tunable from 2.25-4.5 GHz with independent Q-tuning from 3-150. Linearity is improved by using a dual varactor for tuning such that the varactor 3
^rd
order distortion cancels over the range where the MOS varactors are the most nonlinear. This results in an out-of-band IIP3 of 23.5 dBm. The third paper presents an injection locked PLL (ILPLL) at 2 GHz fabricated in a 65nm CMOS process consuming 3.74 mW form 0.9 V. Traditional ILPLLs use a tunable delay line to inject the reference pulse into the oscillator and require delay line calibration to ensure proper timing of the pulse to minimize the reference spur. In this work, an injection locked frequency divider (ILFD) is used to introduce a phase shift in the feedback path of the ILPLL. This has the effect of locking the delay in the ILPLL to a fixed delay line resulting in a simple, low power calibration that can be run in the background. The fourth and final paper in the session leverages a 0.25 μm GaN HEMT process to implement a high SNR track-and-hold. The T/H provides a 98 dB SNR at 200 MHz for greater than 16-bit performance. The primary challenge in using a GaN process for T/H applications is related to the gate leakage associated with the Schottky contact gate. In this work a gate bootstrapping technique is used as well as a two-stage T/H to minimize droop in hold mode.