Radio-frequency switch system having improved intermodulation distortion performance
Radio-frequency (RF) switch circuits are disclosed providing improved switching performance. An RF switch system includes a switch having a stack of field-effect transistors (FETs) connected in series between first and second nodes. A capacitor connected in series with the switch is configured to inhibit a low-frequency blocker signal from mixing with a fundamental-frequency signal in the switch.
1. A radio-frequency (RF) switch system comprising:
a first switch circuit connected between an antenna node and a transmit node;
a second switch circuit connected between the antenna node and a receive node;
a first capacitor connected in series with the first switch circuit between the first switch circuit and the antenna node;
a second capacitor connected in series with the second switch circuit between the second switch circuit and the antenna node;
a first shunt arm connected to the first switch circuit and the transmit node, the first shunt arm including a third switch circuit connected to ground; and
a second shunt arm connected to the second switch circuit and the receive node, the second shunt arm including a fourth switch circuit connected to ground.
2. The switch system of claim 1 wherein at least one of the first and second capacitors is configured to inhibit a low-frequency blocker signal from mixing with a fundamental-frequency signal in the switch.
3. The switch system of claim 1 wherein the first shunt arm includes a third capacitor connected between the third switch circuit and the transmit node, and the second shunt arm includes a fourth capacitor connected between the fourth switch circuit and the receive node.
4. A radio-frequency (RF) switch system comprising:
a first switch circuit connected between an antenna node and a transmit node;
a second switch circuit connected between the antenna node and a receive node;
a first capacitor connected in series with the first switch circuit between the first switch circuit and the antenna node;
a second capacitor connected in series with the second switch circuit between the second switch circuit and the antenna node;
a first shunt arm connected to the first switch circuit and the transmit node, the first shunt arm including a third switch circuit connected to ground and a third capacitor connected between the third switch circuit and the transmit node.
5. A method for fabricating a semiconductor die, the method comprising:
providing a semiconductor substrate;
forming a first switch circuit on the semiconductor substrate so as to be connected between an antenna node and a transmit node;
forming a second switch circuit on the semiconductor substrate so as to be connected between the antenna node and a receive node;
forming a first capacitor on the semiconductor substrate so as to be connected in series with the first switch circuit between the first switch circuit and the antenna node;
forming a second capacitor on the semiconductor substrate so as to be connected in series with the second switch circuit between the second switch circuit and the antenna node;
forming a first shunt arm connected to the first switch circuit and the transmit node, the first shunt arm including a third switch circuit connected to ground; and
forming a second shunt arm connected to the second switch circuit and the receive node, the second shunt arm including a fourth switch circuit connected to ground.
6. The method of claim 5 further comprising forming an insulator layer between the first switch circuit and the semiconductor substrate.
7. A radio-frequency (RF) switch module comprising:
a packaging substrate configured to receive a plurality of components;
a semiconductor die mounted on the packaging substrate, the die including a first switch circuit connected between an antenna node and a transmit node and a second switch circuit connected between the antenna node and a receive node;
a first capacitor connected in series with the first switch circuit between the first switch circuit and the antenna node;
a second capacitor connected in series with the second switch circuit between the second switch circuit and the antenna node;
a first shunt arm connected to the first switch circuit and the transmit node, the first shunt arm including a third switch circuit connected to ground; and
a second shunt arm connected to the second switch circuit and the receive node, the second shunt arm including a fourth switch circuit connected to ground.
8. The switch module of claim 7 wherein at least one of the first and second capacitors is configured to inhibit a low-frequency blocker signal from mixing with a fundamental-frequency signal in the switch.
9. The switch module of claim 7 wherein the first capacitor is part of the same semiconductor die as the first switch circuit.
10. The switch module of claim 7 wherein the first capacitor is part of a second die mounted on the packaging substrate.
11. The switch module of claim 7 wherein the first capacitor is disposed at a location outside of the semiconductor die.