A 2.4 GHz RF CMOS up-conversion mixer for wireless sensor networks nodes
Mixer is one of the main modules of a transmitter system, and its performance will heavily impact the functionality of the entire transmitter. Gilbert cell structure can achieve high degree of RF (Radio Frequency) and LO (Local Oscillator) isolation, thus loosening filtering output requirements. This design employs a resonant LC network as the load to improve gain, increase the output voltage swing, and inhibit the high-order harmonic generation. It uses feedback to improve the linearity of the mixer. The current-reuse bleeding double-balanced mixer operates at 2.4GHz. And the up-conversion mixer uses an intermediate frequency (IF) input frequency of 1.2MHz, a local oscillator (LO) of frequency of 2.4GHz and a RF output frequency of 2.4012GHz. Experimental test chip is realized. Measured results demonstrate −2.01dB conversion gain, and −13dBm input compression point with 11.9mA total current with a 1.8V supply. The current in Gilbert Cell is 2.9mA and the current in buffer is 9mA.