Wake-up receiver
One or more devices, systems, and/or methods are provided. In an example of the techniques presented herein, a wake-up receiver includes a power management unit configured to receive a supply voltage generated from an input signal and generate a current reference. An envelope detector is configured to generate a signal corresponding to transitions in the input signal. A signal processing unit is configured to generate an interrupt signal responsive to detecting a wake-up pattern in the signal from the envelope detector. The envelope detector comprises a first diode threshold compensated by the current reference.
1 . A wake-up receiver, comprising:
a power management unit configured to receive a supply voltage generated from an input signal and generate a bias current;
an envelope detector comprising a first diode, wherein the first diode is threshold compensated by the bias current and configured to generate a signal corresponding to transitions in the input signal; and
a signal processing unit configured to generate an interrupt signal responsive to detecting a wake-up pattern in the signal from the envelope detector.
2 . The wake-up receiver of claim 1 , comprising:
an energy harvester configured to generate the supply voltage based on the input signal.
3 . The wake-up receiver of claim 1 , wherein the first diode comprises:
a compensation transistor having a first gate, a first input, and a first output connected to the first gate;
a rectification transistor having a second gate and a second output connected to the first input; and
a current source connected to the first gate and the second gate and configured to generate the bias current.
4 . The wake-up receiver of claim 3 , wherein the rectification transistor comprises:
a first transistor; and
a second transistor connected in parallel with the first transistor.
5 . The wake-up receiver of claim 3 , wherein the compensation transistor comprises:
a first transistor; and
a second transistor connected to the first transistor.
6 . The wake-up receiver of claim 5 , wherein the second transistor is connected in series with the first transistor.
7 . The wake-up receiver of claim 3 , wherein the rectification transistor and the compensation transistor comprise p-type transistors.
8 . The wake-up receiver of claim 1 , wherein the envelope detector comprises:
a first capacitor connected in parallel with the first diode; and
a current source configured to generate an integer multiple of the bias current connected in parallel with the first diode.
9 . The wake-up receiver of claim 8 , wherein the envelope detector comprises:
a second diode, wherein the second diode is threshold compensated by the bias current;
a second capacitor connected in parallel with the second diode; and
a voltage divider connected in parallel with the second diode.
10 . A system, comprising:
a radio frequency to direct current (RF-DC) converter comprising a first diode threshold, wherein the first diode is compensated by a bias current and configured to generate a supply voltage based on an RF input signal;
a power management unit configured to receive the supply voltage and generate the bias current;
an envelope detector comprising a second diode, wherein the second diode is threshold compensated by the bias current and configured to generate a signal corresponding to transitions in the RF input signal; and
a signal processing unit configured to generate an interrupt signal responsive to detecting a wake-up pattern in the signal from the envelope detector.
11 . The system of claim 10 , comprising:
a storage unit configured to store energy; and
a power on reset unit configured to operate the system in a first mode responsive to the supply voltage generated by the RF-DC converter exceeding a minimum voltage to allow receipt of data in the RF input signal and operate the system in a second mode responsive to the supply voltage generated by the RF-DC converter being sufficient to charge the storage unit.
12 . The system of claim 10 , comprising:
a small loop antenna connected to the RF-DC converter and the envelope detector.
13 . The system of claim 10 , wherein the first diode comprises:
a diode connected compensation transistor having a first gate and a first output;
a rectification transistor having a second gate and a second output connected to the first output; and
a current source connected to the first gate and the second gate and configured to generate the bias current.
14 . The system of claim 13 , wherein:
the rectification transistor comprises:
a first transistor; and
a second transistor connected in parallel with the first transistor, and
the diode connected compensation transistor comprises:
a third transistor; and
a fourth transistor connected in series with the third transistor.
15 . The system of claim 10 , wherein the envelope detector comprises:
a first capacitor connected in parallel with the first diode;
a current source configured to generate an integer multiple of the bias current connected in parallel with the first diode;
a third diode, wherein the third diode is threshold compensated by the bias current;
a second capacitor connected in parallel with the third diode; and
a voltage divider connected in parallel with the third diode.
16 . The system of claim 10 , wherein:
the second diode comprises an n-type diode,
the RF-DC converter comprises a p-type diode threshold compensated by the bias current and connected to the n-type diode,
a sampling capacitor is connected to a node between an input of the p-type diode and an output of the n-type diode; and
a load capacitor is connected to an output of the p-type diode.
17 . A method, comprising:
receiving a radio frequency (RF) input signal;
harvesting energy from the RF input signal to generate a supply voltage;
generating a bias current based on the supply voltage;
generating a signal corresponding to transitions in the RF input signal using a first diode
generating an interrupt signal responsive to detecting a wake-up pattern in the signal; and
compensating a threshold of the first diode using the bias current.
18 . The method of claim 17 , wherein harvesting energy from the RF input signal comprises:
compensating a threshold of an n-type diode using the bias current; and
compensating a threshold of a p-type diode using the bias current, wherein:
the n-type diode is connected to the p-type diode,
a sampling capacitor is connected to a node between an input of the p-type diode and an output of the n-type diode; and
a load capacitor is connected to an output of the p-type diode.
19 . The method of claim 17 , comprising:
detecting a pattern in the transitions in the RF input signal after the supply voltage exceeds a first voltage; and
storing at least some of the energy in an energy storage device responsive to the supply voltage exceeding a second voltage greater than the first voltage.
20 . The method of claim 17 , wherein generating the signal corresponding to transitions in the RF input signal comprises:
generating a first reference signal using the first diode, a first capacitor connected in parallel with the first diode, and a current source configured to generate an integer multiple of the bias current connected in parallel with the first diode; and
generating a second reference signal using a second diode threshold compensated by the bias current, a second capacitor connected in parallel with the second diode, and a voltage divider connected in parallel with the second diode.