Temperature Sensors to Measure the Central Frequency and 3 dB Bandwidth in mmW Power Amplifiers

Abstract

This letter introduces a novel on-chip measurement technique for the determination of the central frequency and 3 dB bandwidth of a 60 GHz power amplifier (PA) by performing low frequency temperature measurements. The temperature sensor is embedded in the same silicon die as the PA, and placed in empty spaces next to it. Results confirm that temperature sensors can be used as functional built-in testers which serve to reduce testing costs and enhance yield as part of self-healing strategies.Index Terms-Built-in test, CMOS millimeter wave integrated circuits, design for testability, frequency response, temperature measurement.

DC Temperature Measurements to Characterize the Central Frequency and 3 dB Bandwidth in mmW Power Amplifiers

“…A differential temperature sensor was implemented in the same IC and placed close to the last stage of the PA in order to monitor its power dissipation. Details of the sensor circuit and the PA + sensor layout can be seen in [2,3,7]. Fig.…”

“…The sensor predicts a 3 dB bandwidth of 1.65 GHz, while for the power gain curve the bandwidth is 1.6 GHz. According to measurements of the S21 parameter reported in [2], the central frequency is at 58.45 GHz and the bandwidth was 1.8 GHz. Note that a 500 MHz step was used in the measurements.…”

“…In a recent letter published in this journal [2], low frequency temperature measurements were proposed to determine the central frequency and the 3 dB bandwidth of a 60 GHz power amplifier (PA). In that work, the PA was driven with two tones whose frequencies were f IN and f IN +5 kHz.…”

“…One disadvantage of this heterodyne approach is the difficulty of generating two high-frequency tones with a small and precise spacing -six order of magnitude difference, in [2]-and on top of that sweep them over a large range. Although it is possible to use two signal generators with external synchronization [2], the complexity of the set-up is still remarkable.…”

“…Although it is possible to use two signal generators with external synchronization [2], the complexity of the set-up is still remarkable. In addition, the measurement requires a lock-in amplifier, or a FFT representation of the measured waveform, to extract the 5 kHz component of the output.…”