US 10,567,154 B1 · Ring oscillator based all-digital Bluetooth low energy transmitter

Abstract

A Bluetooth Low-Energy (BLE) transmitter is presented for used in ultra-low-power radios in short range IoT applications. The power consumption of state-of-the-art BLE transmitter has been limited by the relatively power-hungry local oscillator due to the use of LC oscillators for superior phase noise performance. This disclosure addresses this issue by analyzing the phase noise limit of a BLE TX and proposes a ring oscillator-based solution for power and cost savings. The proposed transmitter features: 1) a wideband all-digital phase locked loop (ADPLL) featuring an fRF/4 RO, with an embedded 5-bit TDC; 2) a 4× frequency edge combiner to generate the 2.4 GHz signal; and 3) a switch-capacitor digital PA optimized for high efficiency at low transmit power levels. These not only help reduce the power consumption and improve phase noise performance, but also enhance the transmitter efficiency for short range applications.

Claims20

Dependent claims

A frequency synthesizer, comprising:

a modulation controller configured to receive a reference signal from a reference source and operates to frequency modulate the reference signal in accordance with a frequency control word;
a phase-locked loop circuit interfaced with the modulation controller to receive a frequency modulated input signal, wherein the phase-locked loop circuit includes a ring oscillator with an embedded time-to-digital converter circuit;
and
a frequency multiplier circuit configured to receive a frequency modulated output signal from the phase-locked loop circuit and increase frequency of the frequency modulated output signal by a multiplier.

1 more element

Dependencies are inferred from the claim text.

Ring oscillator based all-digital Bluetooth low energy transmitter

Life of this patent

Ring oscillator based all-digital Bluetooth low energy transmitter

Life of this patent

Abstract

Claims20