Abstract
This work presents a compact switched-capacitor power detector (PD) with frequency compensation technique in a 65-nm CMOS process. Utilizing self-biased MOSFET as switches, the PD works both at the positive and the negative cycle to increase the dynamic range (DR). The output of traditional power detectors usually change with the variations of input frequencies which make the measurement of PD more difficult. In this design, by adding a feed-forward frequency detection circuit, the load resistors of the power detector are changed according to the input frequencies. Thus, the effect of input frequency variation is minimized. The measured operation frequency of the power detector is from 3 GHz to 5 GHz with a dynamic range of 20 dB with an error of ±2 dB. The variations of the output voltage are reduced from more than 4 dB to ±0.5 dB, achieving a variation of less than ±0.25 dB/GHz. To the authors’ knowledge, it is the first power detector with input frequency compensation. The core of the power detector occupies an area of 0.014mm2 and consumes 2.04mW static power.
Highlights
In a radio frequency (RF) integrated circuit (IC) system, power control is essential for the power amplifier to maintain reliable communications and extend battery life in mobile devices
We demonstrated a power detector with reasonable dynamic range (DR) and frequency detection circuits to compensate the effect of input frequency variations by changing the load resistances
The losses of the RF probes are de-embedded using the S-parameters provided by Cascade
Summary
In a radio frequency (RF) integrated circuit (IC) system, power control is essential for the power amplifier to maintain reliable communications and extend battery life in mobile devices. The power detector is usually used to adjust transmission power, increasing the capacity and quality of the network. Supporting multi-band is a trend in modern communication systems. For different frequency bands, the outputs of PD varies with input frequencies. This variation can be up to several dB, which requires calibration on these frequencies, making the measurement of input powers difficult. To solve this problem, the frequency compensation technique is required. Since modern systems have a large peak-to-average power ratio, this demand the investigation of power detector with wide dynamic range.
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