On-chip millimeter-wave power detection circuit

1. An apparatus for detecting power, comprising:

a power root mean square (RMS) detector;

a high impedance probe for voltage sensing of signals, the probe comprising a metal line connected to the power root mean square (RMS) detector, wherein the metal line is connected to a transmission line, and wherein a dimension of the probe is configured for impedance matching with one or more elements of the power RMS detector wherein the power RMS detector is configured to measure a RMS voltage value of the sensed signals, and wherein the power RMS detector comprises:

an input capacitor coupled to the high-impedance probe;

an n-channel metal-oxide semiconductor (NMOS) transistor coupled to the input capacitor, the transistor being configured to perform a squaring function on the sensed signals; and

an output filter configured to generate a filtered signal based on the squared signals and provide the filtered signal to an output node, wherein a drain of the NMOS transistor is only connected to the output filter.

2. The apparatus of claim 1 , wherein the metal line is connected to the transmission line through a middle metal layer between a metal layer on which the transmission line is fabricated and a ground layer of a multilayer semiconductor substrate.

3. The apparatus of claim 2 , wherein the metal line is connected to the transmission line through a hole in the middle metal layer.

4. The apparatus of claim 2 , wherein the metal line is connected to the transmission line through the middle metal layer by a via.

5. The apparatus of claim 1 , wherein the probe and transmission line have the same electrical potential.

6. The apparatus of claim 1 , wherein a width of the metal line is narrower than a width of the transmission line.

7. The apparatus of claim 1 , wherein a width of the metal line is 0.1 micron, and a width of the transmission line is 4 micron.

8. The apparatus of claim 1 , wherein the output filter is configured to output direct current (DC) components of the squared signals, and wherein the power RMS detector further comprises:

DC load circuitry coupled to the output node and configured to sample the DC components and convert the DC components to the RMS voltage value.

9. The apparatus of claim 8 , wherein the output filter includes:

a bypass capacitor configured to extract RF components at a main frequency of the squared signals to generate a filtered signal; and

a low frequency filter capacitor configured to average baseband frequency components of the filtered signal.

10. The apparatus of claim 9 , wherein the main frequency of the sensed signals operate in a 60 GHz frequency band.

11. A method for power detection, comprising:

sensing signals with a high impedance probe, wherein the probe comprises a metal line connected to a power root mean square (RMS) detector, wherein the metal line is connected to a transmission line, and wherein a dimension of the probe is configured for impedance matching with one or more elements of the power RMS detector; and

measuring a RMS voltage value of the sensed signals via the power RMS detector, wherein the power RMS detector comprises:

an input capacitor coupled to the high-impedance probe;

an n-channel metal-oxide semiconductor (NMOS) transistor coupled to the input capacitor, the transistor being configured to perform a squaring function on the sensed signals; and

an output filter configured to generate a filtered signal based on the squared signals and provide the filtered signal to an output node, wherein a drain of the NMOS transistor is only connected to the output filter.

12. The method of claim 11 , further comprising connecting the metal line to the transmission line through a middle metal layer between a metal layer on which the transmission line is fabricated and a ground layer of a multilayer semiconductor substrate.

13. The method of claim 12 , further comprising connecting the metal line to the transmission line through a hole in the middle metal layer.

14. The method of claim 12 , further comprising connecting the metal line to the transmission line through the middle metal layer by a via.

15. The method of claim 11 , wherein the probe and transmission line have the same electrical potential.

16. The method of claim 11 , wherein a width of the metal line is narrower than a width of the transmission line.

17. The method of claim 11 , wherein a width of the metal line is 0.1 micron, and a width of the transmission line is 4 micron.

18. The method of claim 11 , wherein the output filter is configured to output direct current (DC) components of the squared signals, and wherein the power RMS detector further comprises DC load circuitry coupled to the output node and configured to sample the DC components and convert the DC components to the RMS voltage value.

19. A wireless device, comprising:

an antenna;

a radio-frequency integrated circuit (RFIC) comprising a transmission line coupled to the antenna; and

a power root mean square (RMS) detector; and

a high impedance probe for voltage sensing of signals, the probe comprising a metal line connected to the power RMS detector, wherein the metal line is connected to the transmission line, and wherein a dimension of the probe is configured for impedance matching with one or more elements of the power RMS detector, wherein the power RMS detector is configured to measure a RMS voltage value of the sensed signals, wherein the power RMS detector comprises:

an input capacitor coupled to the high-impedance probe;

an n-channel metal-oxide semiconductor (NMOS) transistor coupled to the input capacitor, the transistor being configured to perform a squaring function on the sensed signals; and

an output filter configured to generate a filtered signal based on the squared signals and provide the filtered signal to an output node, wherein a drain of the NMOS transistor is only connected to the output filter.