A 5GHz 90-nm CMOS all digital phase-locked loop

An all digital phase-locked loop (ADPLL) has been implemented in a 90-nm CMOS process. It uses a phase frequency detector (PFD) connected to two time-to-digital converters (TDC). To save power the TDCs use uneven delay time in the delay line cells. An automatic tuning bank controller selects active bank of the digitally controlled oscillator (DCO), which features three separate tuning banks. The PLL achieves a phase noise of -125 dBc/Hz at 1 MHz offset from a divided-by-2 carrier frequency of 2.58 GHz. The core area is 0.33 mm² and the current consumption is 30 mA from a 1.2 V supply.