bjt state for YIG current driver logic

[yefj]

Hello, i have a circuit shown bellow which is taken from an attached presentation.
Ifi understand it correctly i need to supply DC current for 2u FM coil.
the presentation slide bellow misses info.
i know that R3 R7 for BC807-40 PNP above is for biasing.
I have few questions:
1.At what state do you think the PNP is in?
the table bellow shows the PNP states and i am not sure to what state should i bias the PNP?

2. we have negative feedback feed to the opamp,i can see that the feedback could help with keeping in proper place the PNP biasing.
If i am correct is there a way i could analize how exactly this feedback meachanism works?
Thanks.

--- Updated Oct 1, 2023 ---

UPDATE:
Suppose at some point the VFM voltage rises from V0 to V0+0.01V So V_minus of the opamp rises too,So what causes the voltage on VFM to return to V0?
Thanks.

 

[BradtheRad]

Your schematic operates the transistors yet they don't waste juice when idle. The op amp draws supply juice through either transistor. Although unconventional apparently the author found that it works.

The op amp draws positive polarity from the PNP when necessary. It does this when the output pulls down bias voltage at the PNP, turning it On.

When the op amp outputs 0V or negative, then the PNP should be idle. its bias resistor (200 ohms near the positive supply rail) turns Off the PNP.

Likewise the op amp draws negative polarity from the NPN when necessary. It does this when the output raises bias voltage at the NPN 0.6V above the negative rail.

At other times the NPN turns Off due to the bias voltage being within 0.6V of the negative supply rail.

 

[FvM]

Q1 and Q2 are current boosters. Operation of the basic current source circuit can be analyzed without it. Feedback sets output current so that shunt R2 voltage drop tracks Vin.

Iout = Vin/25 ohm