Multi-stage pulse shaping network
In a discrete supply modulation system, a circuit includes a multi-stage pulse shaping network (PSN) having a first PSN stage having an input configured to receive variable bias supply signals from a power management circuit (PMC) and having an output coupled to one or more second PSN stages with each of the one or more second PSN stages having an output configured to be coupled to a supply (or bias) terminal of a respective one of one or more radio frequency amplifiers. Such an arrangement is suitable for use with transmit systems in mobile handsets operating in accordance with 5 th generation (5G) communications and other connectivity protocols such as 802.11 a/b/g/n/ac/ax/ad/ay and is suitable for use with multiple simultaneous transmit systems including multiple-input, multiple-output (MIMO), uplink carrier aggregation (ULCA) and beamforming.
1. A multi-stage pulse shaping network configured to be coupled to a bias terminal of a radio frequency (RF) amplifier and configured for use in a discrete supply modulation system, the multi-stage pulse shaping network comprising:
(a) a first pulse shaping network (PSN) stage having an input configured to be coupled to a power management circuit (PMC) and having an output;
(b) one or more second PSN stages, each of the one or more second PSN stages physically spaced apart and distant from the first PSN stage and each of the second PSN stages having an input configured to be coupled to the output of the first PSN stage and having an output configured to be coupled to a bias terminal of an RF amplifier; and
(c) a signal path having a first end coupled to the output of the first PSN stage and having a second end coupled to the inputs of the one or more second PSN stages,
wherein the first PSN stage together with the one or more second PSN stages are configured to filter signals resultant from transitions between discrete voltage levels received from the PMC.
2. The multi-stage pulse shaping network of claim 1 wherein the first PSN stage comprises a passive LC filter.
3. The multi-stage pulse shaping network of claim 1 wherein the first PSN stage is implemented utilizing parasitic inductance and/or capacitive characteristics and/or resistive characteristics of at least one of:
(a) the PMC; or
(b) the signal path coupled between the output of the first PSN stage and the input of the second PSN stage.
4. The multi-stage pulse shaping network of claim 1 wherein the first PSN stage is implemented utilizing parasitic inductance and/or capacitive characteristics and/or resistive characteristics of at least:
(a) the PMC;
(b) the signal path coupled between the output of the first PSN stage and the input of the second PSN stage;
(c) an RF amplifier; and
(d) passives components comprising the PSN.
5. The multi-stage pulse shaping network of claim 1 wherein at least one of the first PSN stage and the second PSN stage comprises a reconfigurable filter circuit.
6. The multi-stage pulse shaping network of claim 1 wherein the PSN comprises a plurality of second PSN stages, each of the second PSN stages spaced apart and distant from the first PSN stage and each of the second PSN stages having an input configured to be coupled to the output of the first PSN stage and having an output configured to be coupled to a supply terminal of a corresponding one of a plurality of RF amplifiers.
7. The multi-stage pulse shaping network of claim 1 wherein at least one PSN stage is physically located proximate a PMC and at least one PSN stage is physically located proximate an RF amplifier.
8. The multi-stage pulse shaping network of claim 1 wherein at least one PSN stage is provided entirely from parasitics from one of: (1) parasitics from a PMC; (2) parasitics from the signal path which electrically couples the first stage to the second stage; (3) parasitics from a signal path which electrically couples at least one stage to an RF amplifier; and (4) parasitics from an RF amplifier.
9. The multi-stage pulse shaping network of claim 1 wherein the first PSN stage is a first one of a plurality of first PSN stages and the multi-stage pulse shaping network circuit further comprises a plurality of second PSN stages with each of the second PSN stages coupled to one or more first PSN stages.
10. The multi-stage pulse shaping network of claim 1 wherein the first PSN stage is a first one of a plurality of first PSN stages and the multi-stage pulse shaping network circuit further comprises a plurality of second PSN stages with each of the first PSN stages coupled to two or more second PSN stages.
11. The multi-stage pulse shaping network of claim 1 wherein filtering signals resultant from transitions between discrete voltage levels received from the PMC comprises damping oscillations.