The second method is to vary the input power level. Though this can be done with a simple attenuator between the driver amp and the PA, the response is very non-linear, as the PA must first come out of saturation before the output power can change. Once out of saturation, the first stage is class A biased which means that the drain current is constant regardless of power settings. The addition of an attenuator also adds to the expense of the parts list and to the board size equation, and increases the insertion loss the driver amp must overcome.
SI9112-DEMOBOARD SI9112-DEMOBOARD SI9112DEMOBOARD on stock| ltem | Symbol | Condif ions | Min | Typ | Max | Unit |
| Forward voltage | VF | I F=50mA | | 1 5 | 2.0 | V |
| Reverse current | IR | VR=5V | | | 1 0 | A |
| Peak emission wavelength | Ap | I F=50mA | | 880 | | nm |
| )bSpectral bandwidth | ^ | I F=50mA | | 50 | | nm |
| Radiant intensity | Po | I F=50mA | | 7 6 | | mW |
| Half angle | | | | ±30 | | |
| | | | | | |
| | | ·75 | ·80 | ·1H | ·1L | ·10 | | |
| Parameter | Symbol | Min | Max | Min | Max | Min | Max | Min | Max | Min | Max | Unit | Note |
| | CAS latency=3 | | 7 5 | | 8 | | 10 | | 10 | | 10 | | | |
| CLK cycle time | CAS latency=2 | tcc | | 1000 | | 1000 | 10 | 1000 | 12 | 1000 | 13 | 1000 | ns | 1 |
| CLK to valid | CAS latency=3 | | | 5 4 | | 6 | | 6 | | 6 | | 7 | | |
| output delay | CAS latency=2 | tSAC | | | | | | 6 | | 7 | | 7 | ns | 1 2 |
| Output data | CAS latency=3 | | 2 7 | | 3 | | 3 | | 3 | | 3 | | | |
| hold time | CAS latency=2 | tOH | | | | | 3 | | 3 | | 3 | | ns | 2 |
| CLK high pulse wid | h | tCH | 2 5 | | 3 | | 3 | | 3 | | 3.5 | | ns | 3 |
| CLK low pulse width | tCL | 2 5 | | 3 | | 3 | | 3 | | 3.5 | | ns | 3 |
| Input setup time | tss | 1 5 | | 2 | | 2 | | 2 | | 2.5 | | ns | 3 |
| Input hold time | tSH | 0 8 | | 1 | | 1 | | 1 | | 1.5 | | ns | 3 |
| CLK to output in Low-Z | tSLZ | 1 | | 1 | | 1 | | 1 | | 1 | | ns | 2 |
| CLK to output | CAS latency=3 | | | 5 4 | | 6 | | 6 | | 6 | | 7 | | |
| in Hi-Z | CAS latency=2 | tSHZ | | | | | | 6 | | 7 | | 7 | ns |
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