System and method for reducing or eliminating temperature dependence of a coherent receiver in a wireless communication device
View Patent ↗In accordance with some embodiments of the present disclosure, a method may include generating a first current equal to a bandgap voltage divided by a resistance selected to approximately match a process resistance integral to a receiver. The method may further include generating a second current equal to temperature-dependent current multiplied by a predetermined scaling factor. The method may also include subtracting the second current from the first current to generate a bias current. The method may additionally include providing the bias current to the receiver.
1. A wireless communication element, comprising:
a transmit path configured to convert a digital signal output by digital circuitry into a wireless communication signal;
a control path communicatively coupled to the transmit path and configured to monitor and control one or more operational parameters associated with the transmit path, the control path comprising:
a coherent receiver configured to receive the wireless communication signal; and
a bias circuit electrically coupled to the coherent receiver and configured to generate a bias current for the coherent receiver, wherein the bias current is equal to:
a bandgap voltage supplied to the bias circuit divided by a resistance selected to approximately match a process resistance integral to the coherent receiver; minus
a temperature-dependent current multiplied by a predetermined scaling factors;
the bias current configured to bias a feedback digital-to-analog converter of the coherent receiver, such that the feedback digital-to-analog converter outputs a current proportional to the bias current.
2. A wireless communication element according to claim 1 , the temperature-dependent current including a positive current, a negative current, or a zero current.
3. A wireless communication element according to claim 1 , the temperature-dependent current equal to zero at a particular temperature.
4. A wireless communication element according to claim 3 , wherein the particular temperature is approximately equal to room temperature.
5. A wireless communication element according to claim 1 , the coherent receiver comprising:
a downconverter configured to downconvert the wireless communication signal into a downconverted signal based on an oscillator signal used to upconvert the digital signal into the wireless communication signal; and
an analog-to-digital converter configured to convert the downconverter signal into a second digital signal, the analog-to-digital converter comprising the feedback digital-to-analog converter.
6. A wireless communication element according to claim 1 , the coherent receiver having one or more elements with operational parameters that are a function of temperature.
7. A wireless communication element according to claim 1 , the predetermined scaling factor based at least on characterization of operation of the coherent receiver.
8. A method comprising:
generating a first current equal to a bandgap voltage divided by a resistance selected to approximately match a process resistance integral to a receiver;
generating a second current equal to temperature-dependent current multiplied by a predetermined scaling factor;
subtracting the second current from the first current to generate a bias current; and
providing the bias current to a feedback digital-to-analog converter of the receiver, such that the feedback digital-to-analog converter outputs a current proportional to the bias current.
9. A method according to claim 8 , the temperature-dependent current including a positive current, a negative current, or a zero current.
10. A method according to claim 8 , the temperature-dependent current equal to zero at a particular temperature.
11. A method according to claim 10 , wherein the particular temperature is approximately equal to room temperature.
12. A method according to claim 8 , wherein the feedback digital-to-analog converter is included in an analog-to-digital converter of the receiver.
13. A method according to claim 8 , the receiver having one or more elements with operational parameters that are a function of temperature.
14. A method according to claim 8 , the predetermined scaling factor based at least on characterization of operation of the receiver.
15. A bias circuit comprising:
a bias reference current portion configured to generate a first current equal to a bandgap voltage divided by a resistance selected to approximately match a process resistance integral to a receiver;
a temperature reference current portion configured to generate a second current equal to temperature-dependent current multiplied by a predetermined scaling factor, the temperature reference current portion comprising:
a current proportional to absolute temperature circuit for generating a current proportional to ambient temperature;
a temperature-independent current source for generating a temperature-independent current; and
a summer configured to subtract the temperature-independent current from the current proportional to ambient temperature in order to generate the second current; and
a mirroring portion configured to generate a bias current equal to the first current minus the second current.
16. A bias circuit according to claim 15 , the temperature-dependent current including a positive current, a negative current, or a zero current.
17. A bias circuit according to claim 15 , the temperature-dependent current equal to zero at a particular temperature.