Frequency mixing device
Provided is a FET resistive frequency mixing device having improved RF-LO and IF-LO isolations. The frequency mixing device includes: a field effect transistor (FET), a local oscillation matching circuit connected to a gate of the FET to transfer a local oscillation signal to the gate of the FET, a gate biasing circuit connected to the gate of the FET, a radio frequency (RF) matching circuit having a first terminal connected to a drain side of the FET and a second terminal serving as a RF terminal to receive or output a RF signal, an intermediate frequency (IF) matching circuit having a first terminal connected to the drain side of the FET and a second terminal serving as an IF terminal to receive or output an IF signal, and a series resonance circuit providing a path from the drain of the FET to ground for the local oscillation signal.
1. A frequency mixing device comprising:
a field effect transistor (FET) having a gate, a drain, and a source;
a local oscillation matching circuit connected to the gate of the FET to transfer a local oscillation signal to the gate of the FET;
a gate biasing circuit connected to the gate of the FET to bias the gate of the FET;
a radio frequency (RE) matching circuit having a first terminal connected to a drain side of the FET and a second terminal serving as a RE terminal to receive or output a RF signal;
an intermediate frequency (IF) matching circuit having a first terminal connected to the drain side of the FET and a second terminal serving as an IF terminal to receive or output an IF signal;
a series resonance circuit providing a path from the drain of the FET to ground for the local oscillation signal to allow a portion of the local oscillation signal passing the FET to flow to ground; and
a band-stop filter having a first terminal connected to the drain of the FET and a second terminal connected to the RF matching circuit or the IF matching circuit to reduce the local oscillation signal transferred to the second terminal of the band-stop filter.
2. The frequency mixing device of claim 1 , wherein the series resonance circuit comprises a capacitor and an inductor connected in series to each other.
3. The frequency mixing device of claim 1 , wherein the band-stop filter blocks or reflects at least some portion of the local oscillation signal received by the band-stop filter.
4. The frequency mixing device of claim 1 , wherein the band-stop filter is disposed between the drain of the FET and the first terminal of the RF matching circuit or between the drain of the FET and the first terminal of the IF matching circuit.
5. The frequency mixing device of claim 1 , wherein the band-stop filter is formed in a spiral shape using a spurline.
6. The frequency mixing device of claim 1 , wherein the RF matching circuit comprises a high-pass filter or a band-pass filter configured to deliver a RF output signal having a frequency in which a frequency of the IF signal and a frequency of the local oscillation signal are mixed.
7. The frequency mixing device of claim 1 , wherein the IF matching circuit comprises a low-pass filter or a band-pass filter configured to deliver an IF output signal having a frequency in which a frequency of the RF signal and a frequency of the local oscillation signal are mixed.
8. The frequency mixing device of claim 1 , further comprising:
a drain grounding circuit connected to the second terminal of the band-stop filter to provide a path from the second terminal of the band-stop filter to ground.
9. The frequency mixing device of claim 8 , wherein the drain grounding circuit comprises a radio frequency choke (RFC).
10. The frequency mixing device of claim 1 , wherein the RF matching circuit or the IF matching circuit comprises a grounding path configured to selectively connect the drain side of the FET to ground.