Two Efficient Dual-Band and Wide-Band Low-Power DCO Designs Using Current Starving Gates, DCV and Reconfigurable Schmitt Triggers in 180 nm

Abstract

Digitally controlled oscillators are the main cores in all-digital phase-locked loops (ADPLL), which are important for determining the range of frequency and power consumption in ADPLLs. In the conventional digitally controlled oscillator (DCO) designs, one single band of operation is assigned to the DCO. The following paper presents a new approach in the design of DCOs, which works in dual-band and wide-band modes with a control unit. In dual-band mode, the DCO works in two different ranges of frequencies simultaneously via digital control bits. The wide-band DCO (WBDCO) works in one wider range of frequencies consecutively. It seems that in the wide-band DCO, the gap width for the dual-band DCO (DBDCO) is zero. The previously mentioned designs allow the designer to have standard frequencies with the help of direct or multiplied frequencies. So, we can have a trade-off between power and performance. This means that we can have low power consumption in low-frequency applications and vice versa. The proposed designs are based on using digitally controlled capacitors, current starving gates and Schmitt triggers in critical points of the DCO loop, while preserving coarse and fine tunings. The non-delay linearity factors are clearly investigated and resolved with the use of a new combined control unit. The simulations of the proposed designs are performed in Hspice with a voltage of VDD = 1.8 v in 180 nm CMOS technology for 64-and 128-bit input coarse codes. Our simulation and evaluation results showed that in the dual-band DCO, a 14.8 ps jitter was calculated at 134 MHz with 1.2131 mW power consumption, while in the wide band with overlap mode, a 68.7 ps jitter was measured at 184.61 MHz

A low-power dual band all digital PLL with precision dual mode DCO and digital linearization control circuits

“…This circuit explained in reference [19]. In this section, we will explain the details of the circuit design.…”

“…The digital control bit applied to one oscillator, and the invert of the digital control bit applied to the other oscillator. In this design, low band and (a) Figure. 2 (a) The internal circuit of control unit [19] and (b) The internal circuit of buffer [19] and (c) Internal circuit of coarse stage [19] and (f) Internal circuit of Fine stage [18].…”

“…B. Equal jitter of the proposed dual-band DCO Ref [19] the jitter function of the structure of proposed oscillator was simulated and shows the displacement amount of frequency response to variations in process corners, supply (VDD) and Temperature (PVT) for proposed design.…”

“…The dual band oscillator can cover different standard bands in different frequency multiple or dividers. Our evaluations on mapping the produced bands into standardized ranges summarized in ref [19]. B.…”

“…The oscillator in [13] is based on changing the MOS driving strength dynamically using a fixed capacitance loading with high resolution, but the power consumption by this structure is high. Our recently developed dual band DCO [19] operates in two different frequency ranges. The DCO switches between two frequency bands simply via toggling a band select bit.…”