| 摘要 |
<p>A preamplifier circuit (140) of a preamp (136) configured for measuring microwave noise of a magnetoresistive element (142) biased by a pair of current sources (144 & 146) is disclosed. In a preferred embodiment, the preamplifier circuit (140) includes a differential amplifier (148) disabled from the preamplifier circuit (140) by a amplifier bypass switch (150), one of the pair bias current sources (144 & 146) disabled from the preamplifier circuit (140) and referenced to ground by a current bypass switch (152), a test point (154) communicating with the amplifier bypass switch (150) providing single ended access to the biased magnetoresistive element (142) for measuring the microwave noise of the biased magnetoresistive element (142) relative to the ground reference and a ground point (156) communicating with the ground reference providing the ground reference for measuring the microwave noise of the biased magnetoresistive element (142).</p> |
