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State-of-the art neural recording systems require electronics allowing for transcutaneous, bidirectional data transfer. As these circuits will be implanted near the brain, they must be small and low power. We have developed micropower integrated circuits for recovering clock and data signals over a transcutaneous power link. The data recovery circuit produces a digital data signal from an ac power waveform that has been amplitude modulated. We have also developed an FM transmitter with the lowest power dissipation reported for biosignal telemetry. The FM transmitter consists of a low-noise biopotential amplifier and a voltage controlled oscillator used to transmit amplified neural signals at a frequency near 433 MHz. All circuits were fabricated in a standard 0.5-[micro]m CMOS VLSI process. The resulting chip is powered through a wireless inductive link. The power consumption of the clock and data recovery circuits is measured to be 129[micro]W; the power consumption of the transmitter is measured to be 465 [micro]W when using an external surface mount inductor. Using a parasitic antenna less than 2 mm long, a received power level was measured to be--59.73 dBm at a distance of one meter. Index Terms--Biotelemetry, low-power CMOS circuits, RF telemetry, transcutaneous data link, transmitter.

A fully integrated class-F power amplifier (PA) with reconfigurable harmonic termination over a wide range of frequencies is presented. Reconfigurability is achieved by utilizing on-chip transformers as part of the output matching network. In addition, a stacked transistor architecture was used to boost the output power. The PA was fabricated in a 0.13-\mum CMOS process and packaged in a 20-pin quad flat no-leads package. It was configured to operate at 700, 900, and 1200 MHz with a maximum measured saturated output power of +\24.6 dBm with a power-added efficiency of 48.3%. The measured gain was 16.5 dB and was flat over the entire bandwidth. The total chip area, including pads, is 1.5 mm\,\times\,1.5 mm. [ABSTRACT FROM AUTHOR]

This brief analyzes three different mechanisms for injecting a tuning current into the tank of inductively tuned LC-quadrature oscillators. It is shown that, by controlling how the tuning current is injected into the tank, either by magnetic coupling, direct coupling, or the newly proposed partial coupling, a tradeoff exists between tuning range, phase noise, and power consumption. This leads to a very flexible design methodology where the coupling mechanism can be selected based on system-level requirements, which may change from one design to the next. [ABSTRACT FROM AUTHOR]