WCMDA PA Bias Method For Lower Junction Temperature: SKY65124

This application note describes how SKY65124 may be used with reduced bias control to obtain better thermal performance. It is especially useful for customers who may not have a suitable heat sink available directly below the PA module.

To achieve high Gain (>24 dB), the SKY65124 consists of two stages of amplification. The base current of each amplification stage is controlled by an on-die active bias circuit. Each active bias circuit has its own reference voltage supply, VREF1 and VREF2. The bias voltage (VC_BIAS) is shared by the two active bias circuits. This application note describes the active bias circuit used by SKY65124.

The note explains the use of external supply voltages (VC_BIAS and VREF) and setting limits available to the customer. Test results of key parameters are also given over temperature.