Emissions-suppression circuits
Architectures and techniques relate to selectively implementing certain components to filter emissions. For example, a circuit can include a filter associated with a first frequency range, a first switch, and a second switch. The first switch can be configured to, in a filter state, route a signal through the filter and configured to, in a bypass state, route the signal to an output node while bypassing the filter. The second switch can be configured to, in the filter state, route the signal from the filter to the output node.
1. An emissions-suppression circuit comprising:
a notch filter associated with a frequency range, the notch filter including a first end and a second end;
a first switch configured to, in a filter state, couple an input node to the first end of the notch filter and configured to, in a bypass state, couple the input node to an output node and bypass a second switch; and
the second switch disposed between the second end of the notch filter and the output node, the second switch is a single-pole-single-throw switch configured to selectively activate, the second switch configured to activate in the filter state.
2. The emissions-suppression circuit of claim 1 wherein the frequency range is associated with a public safety frequency band and the notch filter is configured to implement a specification associated with the public safety frequency band.
3. The emissions-suppression circuit of claim 1 wherein the frequency range is about 769 MHz to 775 MHz.
4. The emissions-suppression circuit of claim 1 further comprising a duplexer coupled to the output node and including a receive filter and a transmit filter that are associated with a same frequency band.
5. The emissions-suppression circuit of claim 1 wherein the first switch is a single-pole-double-throw switch.
6. The emissions-suppression circuit of claim 1 wherein the input node is coupled to a power amplifier and the output node is coupled to a duplexer.
7. A radio-frequency module comprising:
a packaging substrate;
a first filter disposed on the packaging substrate and configured to attenuate signals associated with one or more frequencies, the first filter including a first node and a second node;
a first switch disposed on the packaging substrate and configured to, in a filter state, route a signal through the first node of the first filter to the first filter and configured to, in a bypass state, route the signal to an output node while bypassing the first filter and a second switch; and
the second switch disposed on the packaging substrate between the second node of the first filter and the output node and configured to, in the filter state, route the signal from the second node of the first filter to the output node, the second switch is a single-pole-single-throw switch.
8. The radio-frequency module of claim 7 wherein the first switch is a single-pole-double-throw switch.
9. The radio-frequency module of claim 7 wherein the one or more frequencies are associated with a public safety frequency band.
10. The radio-frequency module of claim 7 wherein the first filter is configured to attenuate signals associated with a first frequency range and the radio-frequency module further includes a second filter dispose on the packaging substrate and configured to pass signals associated with a second frequency range that is adjacent to the first frequency range.
11. The radio-frequency module of claim 10 wherein the second filter is a transmit filter that is implemented in a duplexer, the duplexer including a receive filter that is associated with a same frequency band as the transmit filter.
12. A radio-frequency device comprising:
a power amplifier;
a notch filter;
a switch assembly coupled to the power amplifier and the notch filter, the switch assembly including a first switch and a second switch, the notch filter including a first node and a second node, the first switch being configured to, in a filter state, route a signal through the first node of the notch filter to the notch filter and configured to, in a bypass state, route the signal to an output node while bypassing the notch filter and the second switch, the second switch being configured to, in the filter state, route the signal from the second node of the notch filter to the output node, the second switch is a single-pole-single-throw switch;
a controller coupled to the switch assembly and configured to provide a control signal to the switch assembly; and
an antenna coupled to the switch assembly.
13. The radio-frequency device of claim 12 wherein the notch filter is associated with a public safety frequency band.
14. The radio-frequency device of claim 12 wherein the first switch is a single-pole-double-throw switch.
15. The radio-frequency device of claim 12 further comprising a duplexer coupled to the output node, the notch filter is associated with a first frequency range and the duplexer includes a filter that is associated with a second frequency range that is adjacent to the first frequency range.
16. The radio-frequency device of claim 15 wherein the filter of the duplexer is a transmit filter.